CN112703761B - Method and apparatus for measuring a link between terminals in a wireless communication system - Google Patents

Abstract

According to an embodiment of the present disclosure, an operating method of a first terminal for measuring the sidelink channel quality in a wireless communication system is disclosed, the method comprising the following steps: receiving system information from a base station; based on the system information, sending a sidelink channel state information reference signal (CSI‑RS) to a second terminal in a physical sidelink shared channel (PSSCH); and receiving a CSI report based on the sidelink CSI‑RS from the second terminal.

Description

Method and apparatus for measuring a link between terminals in a wireless communication system

Technical Field

The present disclosure relates to a method of measuring a link between terminals in a wireless communication system, and more particularly, to a method and apparatus for measuring sidelink channel quality by using a signal transmitted via a sidelink channel between terminals.

Background Art

In order to meet the growing demand for wireless data services after the commercialization of the fourth generation (4G) communication system, efforts have been made to develop an enhanced fifth generation (5G) communication system or a quasi-5G communication system. For this reason, the 5G communication system or the quasi-5G communication system is referred to as a "super 4G network communication system" or a "post-long term evolution (LTE) system". The 5G communication system defined by the Third Generation Partnership Project (3GPP) is referred to as a new radio (NR) system. In order to achieve high data rates, it is considered to implement the 5G communication system in an ultra-high frequency band (millimeter wave (mmW)) (e.g., 60GHz). In order to reduce the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, technologies such as beamforming, massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antennas have been discussed for the 5G communication system and applied to the NR system. In addition, in order to improve the system network, for 5G communication systems, technologies such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multi-point (CoMP), and interference cancellation have been developed. In addition, for 5G communication systems, advanced coding modulation (ACM) schemes such as hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC) and enhanced network access schemes such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.

The Internet is evolving from a human-centered connected network where humans create and consume information to an Internet of Things (IoT) network through which distributed elements such as objects exchange and process information. Internet of Everything (IoE) technology, which is a combination of big data processing technology and IoT technology connected to a cloud server, is also emerging. In order to realize IoT, technical elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology and security technology are required, so technologies for inter-object connection such as sensor networks, machine-to-machine (M2M) communication or machine type communication (MTC) have been studied recently. In the IoT environment, intelligent Internet technology (IT) services that collect and analyze data generated by connected objects and create new value in human life can be provided. IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances and advanced medical services through the fusion and integration of existing information technology (IT) and various industries.

Therefore, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, M2M communications, and MTC are implemented by 5G communication technologies such as beamforming, MIMO, and array antennas. The application of cloud RAN as a big data processing technology can also be considered an example of the fusion between 5G technology and IoT technology.

As various services can be provided as mobile communication systems develop, a method for efficiently providing such services is required.

Summary of the invention

Technical issues

The present disclosure relates to a method and apparatus for measuring side link channel quality by using a signal transmitted through a side link channel between terminals.

Solution

According to an embodiment of the present disclosure, an operating method of a first terminal for measuring the side link channel quality in a wireless communication system includes: receiving system information from a base station; based on the system information, sending a side link channel state information reference signal (CSI-RS) to a second terminal in a physical side link shared channel (PSSCH); and receiving a CSI report based on the side link CSI-RS from the second terminal.

In addition, the sidelink CSI-RS can be used to measure at least one of reference signal received power (RSRP), channel quality information (CQI), rank indicator (RI), precoder matrix indicator (PMI), CSI-RS resource index (CRI), or layer indicator (LI).

In addition, the system information may include resource configuration information for determining a transmission bandwidth of the PSSCH, wherein the step of transmitting includes transmitting the side link CSI-RS to the second terminal within the transmission bandwidth of the PSSCH indicated by the resource configuration information.

Furthermore, the sidelink CSI-RS may be generated based on a destination ID for sidelink communication, or may be scrambled by using the destination ID.

In addition, the operating method may further include sending a physical sidelink control channel (PSCCH), wherein the sending step includes sending the sidelink CSI-RS to the second terminal within a transmission bandwidth of the PSSCH indicated by the PSCCH.

The operating method may further include transmitting the received CSI report to the base station by using a Medium Access Control (MAC) Control Element (CE) or a Physical Uplink Control Channel (PUCCH).

According to an embodiment of the present disclosure, an operating method of a second terminal for measuring the sidelink channel quality in a wireless communication system includes: receiving a sidelink channel state information reference signal (CSI-RS) from a first terminal in a physical sidelink shared channel (PSSCH); measuring channel state information (CSI) based on the sidelink CSI-RS; and sending a CSI report based on the measurement result of the CSI to the first terminal.

In addition, the step of measuring CSI may include measuring at least one of reference signal received power (RSRP), channel quality information (CQI), rank indicator (RI), precoder matrix indicator (PMI), CSI-RS resource index (CRI) or layer indicator (LI) based on the sidelink CSI-RS.

According to an embodiment of the present disclosure, a first terminal for measuring side link channel quality in a wireless communication system includes: a transceiver; and at least one processor connected to the transceiver, wherein the at least one processor is configured to receive system information from a base station, send a side link channel state information reference signal (CSI-RS) to a second terminal in a physical side link shared channel (PSSCH) based on the system information, and receive a CSI report based on the side link CSI-RS from the second terminal.

In addition, the sidelink CSI-RS can be used to measure at least one of reference signal received power (RSRP), channel quality information (CQI), rank indicator (RI), precoder matrix indicator (PMI), CSI-RS resource index (CRI), or layer indicator (LI).

In addition, the system information may include resource configuration information for determining a transmission bandwidth of the PSSCH, wherein the at least one processor is further configured to send the sidelink CSI-RS to the second terminal within the transmission bandwidth of the PSSCH indicated by the resource configuration information.

Furthermore, the sidelink CSI-RS may be generated based on a destination ID for sidelink communication, or may be scrambled by using the destination ID.

In addition, the at least one processor may be further configured to transmit a physical sidelink control channel (PSCCH) and transmit the sidelink CSI-RS to the second terminal within a transmission bandwidth of the PSSCH indicated by the PSCCH.

Furthermore, the at least one processor may be further configured to transmit the received CSI report to the base station by using a medium access control (MAC) control element (CE) or a physical uplink control channel (PUCCH).

A second terminal for measuring the sidelink channel quality in a wireless communication system comprises: a transceiver; and at least one processor connected to the transceiver, wherein the at least one processor is configured to receive a sidelink channel state information reference signal (CSI-RS) from a first terminal in a physical sidelink shared channel (PSSCH), measure channel state information (CSI) based on the sidelink CSI-RS, and send a CSI report based on the measurement result of the CSI to the first terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for describing a system according to an embodiment of the present disclosure.

FIG. 2 is a diagram illustrating a vehicle-to-everything (V2X) communication method performed via a side link according to an embodiment.

FIG. 3 is a diagram illustrating resource allocation in a V2X system according to an embodiment.

FIG. 4 is a diagram illustrating resource allocation in a V2X system according to another embodiment.

FIG. 5 is a diagram illustrating a method of supporting unicast, groupcast, and broadcast communications in a device-to-device (D2D) system according to an embodiment.

FIG. 6 is a diagram illustrating a method of supporting multicast communication and broadcast communication in a V2X system according to an embodiment.

FIG. 7 is a diagram illustrating a measurement process for unicast communication in a V2X communication system according to an embodiment of the present disclosure.

FIG. 8 is a diagram illustrating a measurement process for unicast communication in a V2X communication system according to another embodiment of the present disclosure.

FIG. 9 is a diagram illustrating a signal processing procedure of a transmitting terminal for V2X communication according to an embodiment of the present disclosure.

FIG. 10 is a diagram illustrating an operation of a V2X receiving terminal according to an embodiment of the present disclosure.

FIG. 11 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

FIG. 12 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

FIG. 13 is a diagram illustrating a method in which a V2X transmitting terminal transmits a destination ID according to another embodiment of the present disclosure.

FIG. 14 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

FIG. 15 is a diagram illustrating a method in which a V2X transmitting terminal transmits a destination ID according to another embodiment of the present disclosure.

FIG. 16 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

FIG. 17 is a diagram illustrating a method of notifying a pair of a transmitting terminal and a receiving terminal according to an embodiment of the present disclosure.

FIG. 18 is a diagram illustrating the operation and process of a terminal for side link measurement according to an embodiment of the present disclosure.

FIG. 19 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

FIG. 20 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

FIG. 21 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

FIG. 22 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

FIG. 23 is a diagram illustrating a structure of a terminal according to an embodiment of the present disclosure.

FIG. 24 is a diagram showing a structure of a base station according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

In the following description of the embodiments, descriptions of technologies that are well known in the art and not directly related to the present disclosure are omitted. This is to clearly convey the gist of the present disclosure by omitting unnecessary explanations.

For the same reason, some elements in the drawings are exaggerated, omitted or schematically shown. Moreover, the size of each element does not fully reflect the actual size. In the drawings, the same or corresponding elements are represented by the same reference numerals.

The advantages and features of the present disclosure and methods of achieving them will become apparent with reference to the embodiments of the present disclosure described in detail below in conjunction with the accompanying drawings. However, the present disclosure can be implemented in many different forms and should not be construed as limited to the embodiments of the present disclosure set forth herein; on the contrary, these embodiments of the present disclosure are provided so that the present disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those of ordinary skill in the art, and the scope of the present disclosure is limited only by the appended claims. In the specification, the same reference numerals represent the same elements.

In this case, it should be understood that each box of the flowchart illustration and the combination of boxes in the flowchart illustration can be implemented by computer program instructions. Because these computer program instructions can be loaded into a processor of a general-purpose computer, a special-purpose computer or a programmable data processing device, the instructions executed by the processor of the computer or another programmable data processing device generate a device for implementing the function described in the flowchart box. Because these computer program instructions can also be stored in a computer-available or computer-readable memory that can instruct a computer or another programmable data processing device to act in a specific manner, the instructions stored in the computer-available or computer-readable memory can produce a manufacturing project including an instruction device for implementing the function described in the flowchart box. Because the computer program instructions can also be loaded into a computer or another programmable data processing device, a series of operating steps can be performed on a computer or other programmable device to generate a computer-implemented process, and therefore the instructions executed on the computer or other programmable device can provide steps for implementing the function described in the flowchart box.

In addition, each box of the flowchart diagram may represent a module, fragment or part of the code, which includes one or more executable instructions for implementing a specific logical function. It should also be noted that in some alternative embodiments, the functions marked in the box may not occur in order. For example, two boxes shown in succession may actually be executed substantially simultaneously, or depending on the functions involved, these boxes may sometimes be executed in reverse order.

In this case, the term "unit" used in the present embodiment refers to a software or hardware component that performs a specific task, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). However, the term "~unit" is not limited to software or hardware. The term "unit" can be configured in an addressable storage medium or configured to operate one or more processors. Therefore, as an example, "~unit" may include components (such as software components, object-oriented software components, class components and task components), processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and variables. The functions provided in components and "~units" can be combined into fewer components and "~units", or can be further divided into additional components and "~units". In addition, components and "~units" can be implemented as one or more central processing units (CPUs) or secure multimedia cards operating in a device. In addition, the "~unit" in the embodiment may include one or more processors.

The embodiments of the present disclosure will be described mainly based on a new radio access network (RAN) (new radio (NR)) on the fifth generation (5G) mobile communication standard specified by the third generation partnership project (3GPP) as a standardization organization for mobile communication standards and a packet core (5G system, 5G core network or next generation (NG) core) as a core network. However, it is obvious to those skilled in the art that the main subject matter of the present disclosure is applicable to other communication systems with similar technical background technologies with slight modifications within the scope not significantly exceeding the scope of the present disclosure.

In the 5G system, a network data collection and analysis function (NWDAF) may be defined to support network automation, wherein NWDAF is a network function for providing a function of analyzing and providing data collected in a 5G network. NWDAF may provide the results of collecting/storing/analyzing information from the 5G network to an unspecified network function (NF), and the analysis results may be used independently in each NF.

In the following, for ease of description, some terms and names defined by the 3GPP Long Term Evolution (LTE) standard (standards for 5G, NR, LTE or similar systems) may be used. However, the present disclosure is not limited to these terms and names and can also be applied to systems conforming to other standards.

In addition, for the convenience of description, the terms used herein for identifying access nodes, terms indicating network entities, terms indicating messages, terms indicating interfaces between network entities, terms indicating various types of identification information, etc. are exemplified. Therefore, the terms used in the present disclosure are not limited, and other terms indicating objects having the same technical meaning may be used.

In order to meet the increased demand for wireless data services after the commercialization of the fourth generation (4G) communication system, efforts have been made to develop an enhanced 5G communication system (or a new radio (NR) system). In order to achieve high data rates, the 5G communication system has been designed to support resources in ultra-high frequency bands (millimeter wave (mmWave)) (e.g., 28GHz). In order to reduce the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, various technologies such as beamforming, massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antennas have been discussed for the 5G communication system. In addition, unlike LTE, the 5G communication system supports various subcarrier spacings including 15kHz, 30kHz, 60kHz, and 120kHz, wherein the physical control channel uses polarization coding and the physical data channel uses low-density parity check (LDPC). In addition, not only discrete Fourier transform extended orthogonal frequency division multiplexing (DFT-S-OFDM) is used, but also cyclic prefix (CP)-OFDM is used as a waveform for uplink transmission. In LTE, hybrid automatic request (HARQ) retransmission in units of transport blocks (TBs) is supported, and in 5G, code block group (CBG)-based HARQ retransmission in which several CBs are grouped can be additionally supported.

In order to improve the system network, for 5G communication systems, various technologies have been developed, such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, vehicle-to-everything (V2X) networks, cooperative communication, coordinated multi-point (CoMP), and interference cancellation.

The Internet is evolving from a human-centered connected network where humans create and consume information to an Internet of Things (IoT) network where distributed elements such as objects exchange and process information through an Internet of Things (IoT) network. Internet of Everything (IoE) technology, which is a combination of IoT technology and big data processing technology connected to a cloud server, is also emerging. In order to realize IoT, various technical components are required, such as sensing technology, wired/wireless communication and network infrastructure, service interface technology and security technology, so technologies for inter-object connection, such as sensor networks, machine-to-machine (M2M) communication or machine type communication (MTC), have been studied recently. In the IoT environment, intelligent information technology (IT) services that collect and analyze data generated by connected objects and create new value in human life can be provided. IoT can be applied to fields such as smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart home appliances and advanced medical services through the fusion and integration of existing information technology (IT) and various industries.

Therefore, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks, M2M communications, and MTC are implemented by 5G communication technologies such as beamforming, MIMO, and array antennas. The application of cloud RAN as a big data processing technology can also be considered as an example of the fusion between 5G communication technology and IoT technology. Therefore, multiple services can be provided to users in a communication system, and a method for providing multiple services within the same duration according to characteristics to provide the multiple services to users and an apparatus using the method are required. Various services provided in the 5G communication system have been studied, and one of these services is a service that meets low latency and high reliability requirements.

In vehicle communications, the standardization of LTE-based V2X in 3GPP Release 14 and Release 15 has been completed based on the D2D communication structure, and attempts have been made to develop 5G NR-based V2X. In NR V2X, unicast communication, groupcast (or multicast) communication, or broadcast communication between terminals will be supported. In addition, unlike LTE V2X, which is intended to provide basic safety information transmission and reception required for vehicle driving, NR V2X is intended to provide further advanced services such as platooning, advanced driving, extended sensors, and remote driving. In order to support various services and scenarios, NR V2X needs to support higher reliability and higher data rates than conventional LTE D2D or LTE V2X. Therefore, link adaptation based on feedback between terminals not supported by LTE D2D or LTE V2X is required, and for this purpose, methods and devices for measuring link quality between terminals are required.

Embodiments of the present specification provide a method and apparatus for measuring a link between terminals to support high reliability and high data rate.

FIG. 1 is a diagram for describing a system according to an embodiment of the present disclosure.

FIG1( a ) shows an example in which all V2X UEs UE- 1 and UE- 2 are located within the coverage of a base station.

All V2X UEs may receive data and control information from a base station via a downlink (DL), or may transmit data and control information to a base station via an uplink (UL). In this case, the data and control information may be data and control information for V2X communication. Alternatively, the data and control information may be data and control information for general cellular communication. In addition, the V2X UE may transmit/receive data and control information for V2X communication via a sidelink (SL).

(b) of FIG1 shows an example in which V2X UE UE-1 among V2X UEs is located within the coverage of the base station and V2X UE UE-2 is located outside the coverage of the base station. The example of (b) of FIG1 may be referred to as partial coverage.

The V2X UE UE-1 located within the coverage of the base station may receive data and control information from the base station via a downlink (DL), or may transmit data and control information to the base station via an uplink (UL).

The V2X UE UE-2 located outside the coverage of the base station cannot receive data and control information from the base station via a downlink, and cannot transmit data and control information to the base station via an uplink.

The V2X UE UE-2 may transmit/receive data and control information for V2X communication to/from the V2X UE UE-1 via a side link.

FIG1( c ) shows an example in which all V2X UEs are outside the coverage of a base station.

Therefore, the V2XUE UE-1 and UE-2 cannot receive data and control information from the base station via the downlink, and cannot transmit data and control information to the base station via the uplink.

V2X UEs UE-1 and UE-2 may transmit/receive data and control information for V2X communication via a side link.

Although the V2X system includes two UEs (i.e., V2X UE UE-1 and UE-2) for ease of description, the present disclosure is not limited thereto. In addition, the uplink and downlink between the base station and the V2X UE may be referred to as a Uu interface, and the side link between the V2X UEs may be referred to as a PC5 interface. Therefore, in the present disclosure, the uplink and downlink and the Uu interface may be used interchangeably, and the side link and the PC5 interface may be used interchangeably.

In addition, in the present disclosure, UE may represent a vehicle supporting vehicle-to-vehicle (V2V) communication, a vehicle or a mobile phone (e.g., a smart phone) supporting vehicle-to-pedestrian (V2P) communication, a vehicle supporting vehicle-to-network (V2N) communication, or a vehicle supporting vehicle-to-infrastructure (V2I) communication. In addition, in the present disclosure, UE may represent a roadside unit (RSU) having a UE function, an RSU having a base station function, or an RSU having a portion of a base station function and a portion of a UE function.

FIG. 2 is a diagram illustrating a V2X communication method performed via a side link according to an embodiment.

As shown in (a) of FIG. 2 , a transmitting (TX) UE and a receiving (RX) UE may perform communication in a one-to-one manner, which may be referred to as unicast communication.

As shown in (b) of FIG. 2 , the transmitting UE and the receiving UE may perform communication in a one-to-many manner, which may be referred to as groupcast or multicast communication.

In (b) of FIG. 2 , UE-1, UE-2, and UE-3 may form one group (i.e., group A) to perform groupcast communication, and UE-4, UE-5, UE-6, and UE-7 may form another group (i.e., group B) to perform groupcast communication. Each UE may perform groupcast communication only within the group to which the UE belongs, and may not perform communication between different groups. Although two groups are formed in (b) of FIG. 2 , the present disclosure is not limited thereto.

In addition, although not shown in FIG. 2 , the V2X UE may perform broadcast communication. Broadcast communication indicates that all V2X UEs receive data and control information transmitted by the V2X transmitting UE via a side link. For example, in FIG. 2 (b), when UE-1 is a transmitting UE for broadcast communication, all UEs (UE-2 to UE-7) may receive data and control information transmitted by UE-1.

FIG. 3 is a diagram illustrating resource allocation in a V2X system according to an embodiment.

All V2X UEs connected to the eNB can obtain system information from the eNB through a system information block (SIB). In this case, the system information may include resource pool information for V2X communication.

3 , V2X-TX1 may represent a V2X transmitting UE that is to perform V2X communication. The V2X transmitting UE TX1 may request resource allocation for V2X transmission from the eNB via the Uu interface.

The eNB may transmit control information for sidelink transmission of the V2X transmission UE TX1 to the V2X transmission UE TX1 via a downlink control channel. In this case, the control information transmitted by the eNB may include resource allocation information for sidelink control information and data information transmission of the V2X transmission UE TX1.

The V2X receiving UE may obtain information about resources to be received by the V2X receiving UE through the system information. For example, when a specific resource pool is configured as a receiving resource pool, the V2X receiving UE may receive all V2X resources of the specific resource pool.

FIG. 4 is a diagram illustrating resource allocation in a V2X system according to another embodiment.

Different from FIG. 3 , in FIG. 4 , the eNB may send information about a transmission resource pool and a reception resource pool that the V2X UE can use to the UE through system information.

A UE that is to transmit V2X data among the UEs receiving the information may randomly select one of the resources in the transmission resource pool, and may transmit the V2X control information and the data information. Alternatively, a UE that is to transmit V2X data may select a transmission resource according to a determined rule.

For example, when the V2X transmitting UE senses the V2X transmitting resource pool within a determined time duration and determines that specific resources are not occupied by another UE, the V2X transmitting UE may transmit V2X control information and data information in the specific resources.

When the specific resource pool is configured as the receiving resource pool, the V2X receiving UE may receive all V2X resources of the specific resource pool, as described with reference to FIG. 3 .

FIG. 5 is a diagram illustrating a method of supporting unicast, groupcast, and broadcast communications in a D2D system according to an embodiment.

In a D2D communication system, whether the D2D communication is unicast communication, multicast communication, or broadcast communication can be determined at a high level through an 8-bit group destination ID sent via a D2D control channel (e.g., a physical sidelink control channel (PSCCH)) and a 16-bit ID sent via a D2D data channel (e.g., a physical sidelink shared channel (PSSCH)).

In more detail, the D2D receiving UE UE-1 may receive the D2D side link control channel and then may obtain an 8-bit group destination ID by performing decoding. In this case, when the 8-bit group destination ID indicates the group of the D2D receiving UE UE-1, the D2D receiving UE UE-1 may decode the D2D data information transmitted in the time/frequency resource indicated by the D2D side link control channel. After decoding the D2D data information, the D2D receiving UE may obtain a 16-bit ID from a media access control protocol data unit (MAC PDU) header. The D2D receiving UE may determine whether data is data transmitted to the D2D receiving UE or data transmitted to another UE through the 16-bit ID.

When the data is not data sent to the D2D receiving UE, the D2D receiving UE may discard the data without sending the data to the upper layer. When the above ID (i.e., 8-bit group destination ID + 16-bit ID) indicates one destination, it can be considered as unicast communication, and when the above ID indicates two or more destinations, it can be considered as multicast communication. In addition, when the above ID indicates an unspecified majority without indicating a specific group, it can be considered as broadcast communication.

FIG. 6 is a diagram illustrating a method of supporting multicast communication and broadcast communication in a V2X system according to an embodiment.

In a D2D system, a sidelink control channel and a sidelink data channel may be time-divided and transmitted.

In the V2X system, the sidelink control channel and the sidelink data channel may be frequency-divided and transmitted. In addition, in the V2X system, unicast communication may not be supported, and the ID may not be transmitted via the sidelink control channel, as shown in FIG5 .

That is, the 24-bit ID may be transmitted via the V2X sidelink data channel, and the V2X receiving UE may determine whether the data is data transmitted to the V2X receiving UE or data transmitted to another UE through the 24-bit ID. When the data is not data transmitted to the V2X receiving UE, the V2X receiving UE may discard the data without transmitting the data to the upper layer. When the 24-bit ID indicates a destination of a specific group, it may be considered as a multicast communication, and when the 24-bit ID indicates an unspecified majority without indicating a specific group, it may be considered as a broadcast communication.

FIG. 7 is a diagram illustrating a measurement process for unicast communication in a V2X communication system according to an embodiment of the present disclosure.

In FIG. 7 , it may be assumed that the link configuration for the unicast link (ie, pairing of the transmitting UE and the receiving UE for V2X unicast communication) has been completed.

The gNB may configure the information for measurement in the UE via SIB. Alternatively, the gNB may configure the information for measurement via UE-specific radio resource control (RRC) information.

In this case, the information used for measurement may include time/frequency resources and period for measurement, and time/frequency resources and reporting period that the UE can report by performing measurement. In this case, the measurement may refer to at least one of reference signal received power (RSRP), channel quality information (CQI), rank indicator (RI), precoder matrix indicator (PMI), CSI-RS resource index (CRI), and layer indicator (LI).

The measurement may be started by sending a request from UE V2X-TX1 via V2X or receiving a request from UE V2X-RX1 via V2X.

For example, when the V2X transmitting UE is to transmit sidelink data by using a specific modulation and coding scheme (MCS) or more modulation and coding schemes, such as (64-quadrature amplitude modulation (QAM) or 256-QAM), the V2X transmitting UE may make a measurement request to the gNB.

Likewise, when the V2X receiving UE is to receive sidelink data, such as (64-QAM or 256-QAM), by using a specific MCS or more MCSs, the V2X receiving UE may make a measurement request to the gNB. In this case, the measurement request may be made through a MAC control element (CE) or may be made via an uplink control channel (e.g., a physical uplink control channel (PUCCH)).

Optionally, when the strength of the received signal of the control channel or the data channel received by the V2X receiving UE from the V2X transmitting UE is equal to or less than a specific threshold, the V2X receiving UE may make a measurement request to the gNB. In this case, the strength of the received signal may be measured by a demodulation reference signal (DMRS) transmitted via a control channel or a DMRS transmitted via a data channel. Information about the threshold may be information obtained by the UE from the gNB through system information or UE-specific RRC information, or may be a value agreed upon in advance between the gNB and the UE.

As another example, as shown in Figure 7, the gNB may send a measurement indication to a V2X transmitting UE and a V2X receiving UE configured with a unicast link. The gNB may send the measurement indication via a MAC CE or via downlink control information (DCI).

Although the gNB sends the measurement indication to both the V2X transmitting UE and the V2X receiving UE in FIG. 7 , the gNB may send the measurement indication only to the V2X transmitting UE or the V2X receiving UE.

When the measurement indication is transmitted only to the V2X transmitting UE or to both the V2X transmitting UE and the V2X receiving UE, the V2X transmitting UE receiving the measurement indication may transmit a measurement signal in a time slot in which the measurement indication is received or after a specific offset from the time slot in which the measurement indication is received. In this case, the measurement signal may be a sidelink synchronization signal for performing sidelink synchronization, a channel state information reference signal (CSI-RS) for measuring sidelink channel quality, a DMRS transmitted via a sidelink control channel, or a DMRS transmitted via a sidelink data channel.

In more detail, when the measurement signal is a sidelink synchronization signal, the V2X transmitting UE that receives a measurement indication from the gNB through a MAC CE or a DCI may send the sidelink synchronization signal in the time slot in which the measurement indication is received or after a specific offset from the time slot in which the measurement indication is received (or after a specific offset from the symbol of the time slot in which the measurement indication is received).

As another example, when the measurement signal is a CSI-RS for measuring the side link channel quality, the V2X transmitting UE that receives a measurement indication from the gNB through a MAC CE or a DCI may send the side link CSI-RS in the time slot in which the measurement indication is received or after a specific offset from the time slot in which the measurement indication is received (or after a specific offset of a symbol from the time slot in which the measurement indication is received).

As another example, when the measurement signal is a DMRS sent via the sidelink control channel, the V2X transmitting UE that receives the measurement indication from the gNB through the MAC CE or DCI may send the sidelink control information in the time slot in which the measurement indication is received or after a specific offset from the time slot in which the measurement indication is received (or after a specific offset of a symbol from the time slot in which the measurement indication is received).

As another example, when the measurement signal is a DMRS sent via a sidelink data channel, a V2X transmitting UE that receives a measurement indication from a gNB through a MAC CE or DCI may send sidelink data information in a timeslot in which the measurement indication is received or after a specific offset from the timeslot in which the measurement indication is received (or after a specific offset of a symbol from the timeslot in which the measurement indication is received).

When the sidelink measurement signal is a CSI-RS for measuring the sidelink channel quality or a DMRS transmitted via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel transmitted by the V2X transmitting UE. That is, when there is no sidelink data transmission, the V2X transmitting UE does not transmit the sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel scheduled by the gNB for sidelink transmission through DCI. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of the resource used to transmit the V2X sidelink data channel, wherein the resource is obtained by the V2X transmitting UE through a sensing process in a resource pool, wherein the resource pool is configured through system information or RRC for sidelink transmission from the gNB. In the above examples, the sensing process may refer to energy measurement of a sidelink control channel or a sidelink data channel, or may refer to RSRP measurement from a DMRS transmitted via a sidelink control channel or a sidelink data channel. As another example, the sensing process may refer to a decoding process of control information transmitted via a sidelink control channel. As another example, the sensing process may refer to the above two operations (ie, energy measurement and decoding process of control information).

The V2X receiving UE may receive and decode the sidelink control information from the V2X transmitting UE. The V2X receiving UE may obtain the time and/or frequency resource information of the sidelink data channel from the decoded control information. The V2X receiving UE may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting UE may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving UE. As another example, information about the bandwidth of the transmitted sidelink measurement signal may be sent by the V2X transmitting UE to the V2X receiving UE via the sidelink control information. Therefore, in the above example, the V2X receiving UE may decode the sidelink control information and may obtain information about the bandwidth of the sidelink measurement signal.

When the measurement indication is transmitted only to the V2X receiving UE or to both the V2X transmitting UE and the V2X receiving UE, the V2X receiving UE receiving the measurement indication may receive a measurement signal from the V2X transmitting UE in a time slot in which the measurement indication is received or after a specific offset from the time slot in which the measurement indication is received. The V2X receiving UE receiving the measurement signal may measure the sidelink measurement signal and may report the measurement result to the V2X transmitting UE. In this case, information on resources for reporting the measurement result may be explicitly included in a MAC CE or DCI through which the measurement indication is transmitted by the gNB.

As another example, the resource for reporting the measurement result may be in a linked or associated relationship with the resource for sending the measurement signal. That is, the V2X receiving UE that receives the measurement signal may know the information about the resource for reporting the measurement result by using the associated relationship. The V2X sending UE that sends the measurement signal may receive the measurement result reported by the V2X receiving UE to the V2X sending UE by using the associated relationship. The associated relationship between the resource for sending the measurement signal and the source for reporting the measurement result may be established by using any of a variety of methods. For example, the resource for reporting the measurement result may be determined by using a sequence index of the measurement signal, a time resource for sending the measurement signal, a frequency resource, or a combination of a time resource and a frequency resource.

In more detail, a specific sequence index used to send a measurement signal may be referred to as a time resource or a frequency resource for measurement reporting.

For example, the gNB may allocate time resources for measurement reporting (the index of the time slot where the measurement report is performed or the symbol index of the time slot where the measurement report is performed) to each UE through the V2X link measurement configuration. The V2X UE may determine the frequency resources for performing measurement reporting (through the index of the resource block where the measurement report is performed) through the sequence index of the measurement signal.

Instead, the gNB can allocate frequency resources for measurement reporting to each UE through the V2X link measurement configuration. The V2X UE can determine the time resources for performing measurement reporting through the sequence index of the measurement signal.

As another example, without configuration from the gNB, the V2X UE may perform measurement reporting after a specific time offset from a time point at which the measurement signal is received (e.g., after K symbols). In this case, the frequency resource for the measurement report may be derived by at least one of a sequence index of the measurement signal, a time resource at which the measurement signal is transmitted, and a frequency resource at which the measurement signal is transmitted.

As another example, both the time resource and the frequency resource for the measurement report may be derived through at least one of a sequence index of the measurement signal, a time resource for transmitting the measurement signal, and a frequency resource for transmitting the measurement signal.

As another example, the UE that transmits the measurement signal may transmit at least one information of a time resource or a frequency resource in which measurement reporting can be performed to the UE that is to perform measurement reporting.

The V2X transmitting UE V2X-TX1 receiving the measurement report from the V2X receiving UE V2X-RX1 may send the measurement report to the gNB. In this case, the measurement result of the V2X receiving UE V2X-RX1 reported by the V2X transmitting UE V2X-TX1 to the gNB may be sent via MAC CE or PUCCH.

As another example, the V2X receiving UE V2X-RX1 performing measurement reporting may report information directly to the gNB without sending the UE V2X-TX1 reporting information to the V2X. In this case, the resources may be explicitly included in the information of the gNB's measurement indication, or the resources may be determined by the UE through an association with the measurement signal as described above.

The measurement indication for the V2X receiving UE can be used to indicate whether the channel quality measured by the V2X receiving UE is reported to the V2X transmitting UE or to the gNB.

As another example, the gNB may configure, via UE-specific RRC or common RRC signaling, whether to report the channel quality measured by the V2X receiving UE to the V2X sending UE or to the gNB itself in the V2X UE.

The gNB receiving the measurement report from the UE may perform sidelink scheduling based on the measurement report. That is, the gNB may send DCI for the sidelink to the V2X transmitting UE, and the V2X transmitting UE receiving the DCI may send sidelink control information and data information to the V2X receiving UE.

Although the measurement signal is transmitted from the V2X transmitting UE V2X-TX1 in FIG. 7 , the same description is applicable to the case where the measurement signal is transmitted from the V2X receiving UE V2X-RX1.

The gNB may indicate whether the measurement signal is to be sent by the V2X transmitting UE or the V2X receiving UE through an indicator included in the measurement indication. For example, when the indicator included in the measurement indication indicates "1", the UE receiving the measurement indication may send the measurement signal, and when the indicator indicates "0", the UE receiving the measurement indication may receive the measurement signal. When the V2X receiving UE sends the measurement signal, the V2X transmitting UE may receive the measurement signal and may measure the channel quality.

In addition, since unicast communication has been mainly described in FIG. 7 , it has been assumed that there is one V2X transmitting UE V2X-TX1 and one V2X receiving UE V2X-RX1. However, the process described with reference to FIG. 7 may be applied to groupcast communication in which two or more UEs exist. For example, when it is assumed that there is another V2X receiving UE V2X-RX2, the V2X receiving UE V2X-RX2 may send a measurement request to the gNB. The gNB may send a measurement indication to the V2X receiving UE V2X-RX2. The V2X receiving UE V2X-RX2 that receives the measurement signal from the V2X transmitting UE V2X-TX1 may perform side link measurement like the V2X receiving UE V2X-RX1, and may send the measurement result to the V2X transmitting UE V2X-TX1 or the gNB. When the V2X transmitting UE V2X-TX1 receives measurement results from two or more receiving UEs (i.e., V2X receiving UEs V2X-RX1 and V2X-RX2), the V2X transmitting UE V2X-TX1 may report the measurement results of each of the V2X receiving UEs V2X-RX1 and V2X-RX2 to the gNB, or may multiplex the measurement results and may send the measurement results via one channel.

In FIG. 7 , it has been assumed that both the V2X transmitting UE and the V2X receiving UE exist within the coverage of the gNB. In addition, a resource allocation method in which the V2X transmitting UE operates in an RRC connection state with the gNB (scheduling the V2X transmitting UE using transmission resources of the sidelink control information and data information from the gNB) has been assumed. However, this is merely an example, and the present disclosure is not limited thereto. The V2X transmitting UE and the V2X receiving UE may operate in various situations.

For example, the V2X transmitting UE may be present within the coverage of the gNB, and the V2X receiving UE may be present outside the coverage. As another example, the V2X transmitting UE may be present within the coverage of gNB-1, and the V2X receiving UE may be present within the coverage of gNB-2. In this case, the process of FIG. 7 may be repeated.

Both the V2X transmitting UE and the V2X receiving UE may exist outside the coverage of the gNB. In this case, the V2X transmitting UE and the V2X receiving UE may not perform RRC connection configuration with the gNB. Therefore, in this case, in FIG7 , the operation of the V2X transmitting UE and the V2X receiving UE receiving configuration information for sending a side link measurement signal from the gNB may be omitted. In addition, the process of the V2X transmitting UE and the V2X receiving UE requesting the gNB to send a side link measurement signal, the process of the V2X transmitting UE and the V2X receiving UE receiving an indication for sending a side link measurement signal from the gNB, and the process of the V2X transmitting UE sending the side link channel quality report result received from the V2X receiving UE to the gNB may be omitted.

As described above, the V2X transmitting UE may directly select a transmission resource in a preconfigured resource pool through a sensing process. The sidelink measurement signal may be transmitted together with data information in the transmission resource for transmitting the sidelink data information. That is, the V2X transmitting UE may determine whether there is sidelink control information and/or data information to be transmitted, and when the information exists, the sidelink measurement signal may be transmitted. Otherwise, the V2X transmitting UE may not transmit the sidelink measurement signal, or when there is a sidelink measurement signal being transmitted, the sidelink measurement signal may be stopped from being transmitted.

As another example, the V2X transmitting UE may be present within the coverage of the gNB, but may operate in a state where no RRC connection is configured with the gNB. In this case, as described above, the V2X transmitting UE may directly select a transmission resource in a resource pool configured by the gNB through a sensing process. In this case, the process in which the V2X transmitting UE requests the gNB to transmit a sidelink measurement signal, the process in which the V2X transmitting UE receives an indication from the gNB for transmitting the sidelink measurement signal, and the process in which the V2X transmitting UE transmits the sidelink channel quality report result received from the V2X receiving UE to the gNB may be omitted.

FIG. 8 is a diagram illustrating a measurement process for unicast communication in a V2X communication system according to another embodiment of the present disclosure.

In FIG8 , it is assumed that link configuration of the transmitting and receiving UEs for V2X unicast communication has been completed in advance as described with reference to FIG7 . Although the measurement process is performed separately from the V2X communication in FIG7 , in FIG8 , measurement is performed by using the V2X communication without a separate measurement process.

The V2X transmitting UE and the V2X receiving UE may receive information fragments for unicast communication through system information, wherein the system information may be transmitted through SIB or UE-specific RRC signaling transmitted to each UE. In this case, the information transmitted by the gNB may include resource pool information for unicast communication, and the resource pool information may be configured differently from the resource pool for multicast communication and the resource pool for broadcast communication.

For example, a resource pool for unicast communication may be orthogonal along the time-frequency axis to a resource pool for groupcast and broadcast communication. In addition, there may be one or more resource pools for unicast communication, and each resource pool may be implicitly or explicitly mapped to a subcarrier spacing that may be used in the resource pool.

When each resource pool is implicitly mapped to a subcarrier spacing, each resource pool may be mapped to a subcarrier spacing in the order of decreasing (or increasing) index of the resource pool. That is, resource pool index 1 may use a subcarrier spacing of 15 kHz, and resource pool index 2 may use a subcarrier spacing of 30 kHz.

When each resource pool is explicitly mapped to a subcarrier spacing, information about the subcarrier spacing that can be used in each resource pool may be included in the resource pool configuration information. In this case, each resource pool may include at least one of a transmission resource pool for V2X transmission and a reception resource pool for V2X reception.

A UE that desires V2X data transmission among V2X UEs that receive resource pool information through system information or UE-specific RRC signaling may request resources for V2X data transmission from the gNB. In this case, V2X transmission resources may be requested via PUCCH transmitted over the Uu interface.

A UE among V2X UEs that desires V2X data reception may request resources for V2X data reception from the gNB. In this case, V2X reception resources may be requested via the PUCCH transmitted over the Uu interface.

The PUCCH for requesting V2X transmission resources and the PUCCH for requesting V2X reception resources may be different from each other. For example, the PUCCH for requesting V2X transmission resources and the PUCCH for requesting V2X reception resources may use different time/frequency resources. The UE may identify which PUCCH is the PUCCH for requesting transmission resources and which PUCCH is the PUCCH for requesting reception resources. For example, information about which PUCCH is the PUCCH for requesting transmission resources and which PUCCH is the PUCCH for requesting reception resources may be included through a UE-specific or common configuration for PUCCH transmission.

The UE requesting resources for V2X transmission may obtain information about at least one of time resources or frequency resources for V2X transmission from the gNB through DCI. Similarly, the UE requesting resources for V2X reception may obtain information about at least one of time resources or frequency resources for V2X reception from the gNB through DCI. The process in which the V2X reception UE requests the gNB for V2X reception resources and the process in which the V2X reception UE receives information about the V2X reception resources from the gNB through DCI may be omitted.

After receiving the DCI, the UE may need to determine whether the DCI includes resource information for V2X transmission or resource information for V2X reception. To this end, different DCI formats may be used. For example, DCI format A may be DCI including information related to V2X transmission, and DCI format B may be DCI including information related to V2X reception. As another example, an indicator indicating whether the DCI is DCI related to transmission or DCI related to reception may be used in the same DCI format. For example, when "0" is obtained through a 1-bit identifier in the DCI, DCI for transmission may be indicated, and when "1" is obtained, DCI for reception may be indicated. When the process of the V2X receiving UE (i.e., the process of the V2X receiving UE requesting V2X reception resources from the gNB and the process of the V2X receiving UE receiving information about V2X reception resources through the DCI from the gNB) is omitted, the field of the corresponding DCI may be omitted.

A UE that receives DCI for V2X transmission from a gNB may send a reference signal for measurement or sidelink control information and data information in the time/frequency resources indicated by the DCI. As described with reference to FIG. 7 , when the sidelink measurement signal is a CSI-RS for measuring the quality of the sidelink channel or a DMRS sent via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel sent by the V2X transmitting UE. That is, when there is no sidelink data to be sent, the V2X transmitting UE does not send a sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel for sidelink transmission scheduled by the V2X transmitting UE through the DCI from the gNB. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of a resource for sending a V2X sidelink data channel obtained by the V2X transmitting UE through a sensing process in a resource pool, wherein the resource pool is configured through system information or RRC for sidelink transmission from the gNB. In the above examples, the sensing process may refer to energy measurement of a sidelink control channel or a sidelink data channel, or may refer to RSRP measurement from a DMRS sent via the sidelink control channel or the sidelink data channel. As another example, the sensing process may refer to a decoding process of control information sent via the sidelink control channel. As another example, the sensing process may refer to the above two operations (i.e., energy measurement and decoding process of control information).

A UE that receives DCI for V2X reception from a gNB may receive a reference signal for measurement or sidelink control information and data information in a time/frequency resource indicated by the DCI. The V2X receiving UE may measure channel quality by using a DMRS transmitted via at least one of a sidelink control channel and a sidelink data channel that transmit the sidelink control information and data information. As another example, the V2X receiving UE may measure channel quality by receiving a reference signal for measurement. In this case, the channel quality may include at least one of a reference received power (RSRP), a channel quality information (CQI), a rank indicator (RI), a precoder matrix indicator (PMI), a CSI-RS resource index (CRI), and a layer indicator (LI).

In more detail, the V2X receiving UE may receive and decode the sidelink control information from the V2X transmitting UE. The V2X receiving UE may obtain the time and/or frequency resource information of the sidelink data channel from the decoded control information. The V2X receiving UE may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting UE may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving UE. As another example, the information about the bandwidth of the transmitted sidelink measurement signal may be sent to the V2X receiving UE by the V2X transmitting UE through the sidelink control information. Therefore, in the above example, the V2X receiving UE may decode the sidelink control information and may obtain information about the bandwidth of the sidelink measurement signal.

The V2X receiving UE may report the channel quality measured by the V2X receiving UE to the V2X sending UE or the gNB. In this case, the gNB may indicate whether to report the channel quality to the V2X sending UE or to the gNB through the DCI for V2X reception (sidelink grant of RX in FIG8 ). As another example, in the V2X UE, whether to report the channel quality to the V2X sending UE or to the gNB is configured by the gNB through UE-specific RRC or common RRC signaling.

The resources used for the measurement report may be explicitly included in the grant information (sidelink grant for RX) for the V2X transmitting UE, or may be explicitly included in the sidelink control information sent by the V2X transmitting UE to the V2X receiving UE. As another example, as described with reference to FIG. 7 , the V2X receiving UE may determine the resources used for the measurement report by associating the time resources and frequency resources with the control information or data information for the sidelink transmission sent by the V2X transmitting UE.

When the V2X transmitting UE receives the channel quality measurement report, the V2X transmitting UE may transmit information to the gNB. In this case, the channel quality measurement report may be sent by a MAC CE sent via a PUCCH or a PUSCH. The V2X transmitting UE or the gNB receiving the channel quality measurement report may adjust the number of repeated transmissions or the aggregation level of the next V2X control channel, the number of repeated transmissions or the modulation order of the V2X data channel, and the channel coding rate based on the channel quality measurement report. When the process of the V2X receiving UE (i.e., the process of the V2X receiving UE requesting the gNB for V2X receiving resources and the process of the V2X receiving UE receiving information about the V2X receiving resources through the DCI from the gNB) is omitted, the field of the corresponding DCI may be omitted.

Because unicast communication is mainly described in FIG8, it is assumed that there is one V2X transmitting UE V2X-TX1 and one V2X receiving UE V2X-RX1. However, the process described with reference to FIG8 can be applied to groupcast communication in which there are two or more receiving UEs. For example, when it is assumed that there is another V2X receiving UE V2X-RX2, the V2X receiving UE V2X-RX2 may send a request for sidelink reception to the gNB. The gNB may send control information for sidelink reception (sidelink grant for RX) to the V2X receiving UE V2X-RX2. The V2X receiving UE V2X-RX2 that receives the sidelink control information and data from the V2X transmitting UE V2X-TX1 may perform sidelink measurement like the V2X receiving UE V2X-RX1, and may send the measurement result to the V2X transmitting UE V2X-TX1 or the gNB. When the V2X transmitting UE V2X-TX1 receives measurement results from two or more receiving UEs (i.e., V2X receiving UEs V2X-RX1 and V2X-RX2), the V2X transmitting UE V2X-TX1 may report the measurement results of each of the V2X receiving UEs V2X-RX1 and V2X-RX2 to the gNB, or may multiplex the measurement results and may transmit the measurement results via one channel.

In FIG8, it has been assumed that the V2X transmitting UE and the V2X receiving UE exist within the coverage of the gNB, as shown in FIG7. A resource allocation method in which the V2X transmitting UE operates in an RRC connection state with the gNB (scheduling the V2X transmitting UE using transmission resources of the sidelink control information and data information from the gNB) has been assumed. However, this is only an example, and the present disclosure is not limited thereto. The V2X transmitting UE and the receiving UE may operate in various situations.

For example, the V2X transmitting UE may be within the coverage of the gNB, and the V2X receiving UE may be outside the coverage. As another example, the V2X transmitting UE may be within the coverage of gNB-1, and the V2X receiving UE may be within the coverage of gNB-2. In this case, the process of Figure 8 may be repeated.

Both the V2X transmitting UE and the V2X receiving UE may exist outside the coverage of the gNB. In this case, the V2X transmitting UE and the V2X receiving UE may not perform RRC connection configuration with the gNB. Therefore, in this case, in FIG7 , the operation of the V2X transmitting UE and the V2X receiving UE receiving configuration information for sending a side link measurement signal from the gNB may be omitted. In addition, the process of the V2X transmitting UE and the V2X receiving UE requesting the gNB to send a side link measurement signal, the process of the V2X transmitting UE and the V2X receiving UE receiving an indication for sending a side link measurement signal from the gNB, and the process of the V2X transmitting UE sending the side link channel quality report result received from the V2X receiving UE to the gNB may be omitted.

As described above, the V2X transmitting UE may directly select a transmission resource in a preconfigured resource pool through a sensing process. The data information and the side link measurement signal may be transmitted together in the transmission resource for transmitting the side link data signal. That is, the V2X transmitting UE may determine whether there is side link control information and/or data information to be transmitted, and when the information exists, the side link measurement signal may be transmitted. Otherwise, the V2X transmitting UE may not transmit the side link measurement signal, or when there is a side link measurement signal being transmitted, the V2X transmitting UE may stop transmitting the side link measurement signal.

As another example, the V2X transmitting UE may be present within the coverage of the gNB, but may operate in a state where no RRC connection is configured with the gNB. In this case, as described above, the V2X transmitting UE may directly select a transmission resource in a resource pool configured by the gNB through a sensing process. In this case, the process in which the V2X transmitting UE requests the gNB to transmit a sidelink measurement signal, the process in which the V2X transmitting UE receives an indication from the gNB for transmitting the sidelink measurement signal, and the process in which the V2X transmitting UE transmits a sidelink channel quality report received from the V2X receiving UE to the gNB may be omitted.

FIG. 9 is a diagram illustrating a signal processing procedure of a transmitting terminal for V2X communication according to an embodiment of the present disclosure.

The V2X transmitting terminal may obtain the ID (destination ID) information of the V2X receiving terminal including K bits from the higher layer. In this case, in V2X unicast communication, the ID information may be the ID indicating the receiving terminal. In V2X multicast communication, the ID information may be the ID indicating the receiving group.

The V2X transmitting terminal may generate side link control information and may add a cyclic redundancy check (CRC) to the generated side link control information. That is, when it is assumed that the side link control information includes A bits and the CRC includes L bits, the side link control information to which the CRC is added may include A+L bits.

In this case, some or all of the K bits of the ID may be masked by a CRC including L bits constituting the sidelink control information. In more detail, when the size of the ID is K bits and K>L, the most significant bits (MSB) L bits or the least significant bits (LSB) L bits of the K bits may be used for the CRC mask. In this case, the CRC mask may refer to performing a bitwise exclusive OR (XOR) operation on the L bits constituting the CRC and the MSB L bits (or LSB L bits) of the K bits constituting the ID. The remaining (K-L) bits of the K bits constituting the ID that are not used for the CRC mask may be sent in a field of the sidelink control information (SCI), or may be sent through a header of a MAC PDU sent via a sidelink data channel.

There may be other combinations as follows: L bits of the K bits constituting the ID may be used for the CRC mask, N bits of the remaining (K-L) bits may be sent in the field of the sidelink control information (K-L>N), and the remaining (K-L-N) bits may be sent through the header of the MAC PDU.

As another example, when the size of the ID is K bits, the number of bits of the CRC is L, and K = L, all K bits constituting the ID can be used for the CRC mask. As another example, when K < L, the K bits constituting the ID can be used for the CRC mask by performing an XOR operation on the MSB K bits or the LSB K bits of the L bits constituting the CRC.

The V2X transmitting terminal may perform channel coding on the side link control information to which the CRC masked with the destination ID is added.

The channel-coded side link control information may be scrambled by using a sequence generated by using at least one of a cell ID, a transmitting terminal ID (source ID), and a receiving terminal ID (destination ID) as an initial value. In this case, scrambling may be performed by performing a modulo 2 operation on the sum of the bits constituting the side link control information and the bits constituting the scrambling sequence. For example, when it is assumed that the bits constituting the side link control information are (0), b(1), ..., and b(M-1) and the bits constituting the scrambling sequence are c(i) (in this case, i ranges from 0 to sequence length -1), scrambling may be performed by performing a modulo 2 operation on the result of b(i)+c(i).

When the V2X transmitting terminal masks the CRC by the destination ID, the scrambling operation of FIG9 is similar to the CRC masking operation and thus may be omitted.

Channel-coded sidelink control information (when scrambling is not performed) or scrambled sidelink control information may be generated as symbols through a modulation process and may be mapped to resources (resource elements) of a sidelink control channel.

FIG. 10 is a diagram illustrating an operation of a V2X receiving terminal according to an embodiment of the present disclosure.

The V2X receiving terminal may obtain a destination ID that can be used by the V2X receiving terminal from a higher layer. In this case, the destination ID may be one of an ID for unicast communication, an ID for multicast communication, and an ID for broadcast communication. Although the time point at which the destination ID is obtained from the higher layer is the first starting point in FIG. 10 , this is merely an example, and the present disclosure is not limited thereto. That is, in FIG. 10 , the time point at which the ID is obtained from the higher layer may be any time point before the V2X receiving terminal performs CRC demasking.

The V2X receiving terminal that receives the side link control information from the V2X transmitting terminal may decode the side link control information and may perform CRC demasking by performing an XOR operation on the ID obtained by the V2X receiving terminal from the higher layer and the CRC constituting the side link control information.

The V2X receiving terminal may perform a CRC operation by using a demasked CRC, and when the CRC operation is successful, the V2X receiving terminal may obtain the location of the time/frequency resources of the sidelink data information from the sidelink control information, and may decode the sidelink data information.

When the CRC operation is unsuccessful, the V2X receiving terminal may delete the side link control information from the buffer without storing the side link control information.

FIG. 11 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

Although the destination ID of the receiving terminal is CRC-masked and transmitted in FIG10, in FIG11, part of the information about the destination ID of the receiving terminal is CRC-masked and transmitted, and the remaining part of the information about the destination ID is transmitted through the bit field of the side link control information. As in FIG10, in FIG11, the time point at which the destination ID is obtained from the higher layer can be any time point before the terminal performs CRC demasking.

The V2X receiving terminal that receives the side link control information from the transmitting terminal may decode the side link control information and may perform CRC demasking by performing an XOR operation on the CRC constituting the side link control information and the ID obtained by the V2X receiving terminal from a higher layer.

The V2X receiving terminal may perform a CRC operation by using the demasked CRC, and when the CRC operation is unsuccessful, the V2X receiving terminal may delete the side link control information from the buffer without storing the side link control information.

When the CRC operation is successful, the V2X receiving terminal may obtain the remaining information of the destination ID from the bit field of the side link control information, and may check whether the ID in the bit field matches the ID obtained by the V2X receiving terminal from the higher layer.

When the IDs match, the V2X receiving terminal can obtain the location of the time/frequency resources of the sidelink data information indicated by the sidelink control information, and can decode the sidelink data information.

Although not shown in FIG. 11 , the V2X receiving terminal can construct a destination ID by using some information of the destination ID used for CRC demasking and the remaining information of the destination ID transmitted through the bit field of the side link control information, and can determine whether the destination ID matches the destination ID obtained by the V2X receiving terminal from the higher layer.

For example, it may be assumed that the destination ID includes K bits and L bits are used for CRC masking. In this case, the V2X receiving terminal may perform CRC demasking by using the MSB L bits or LSB L bits of the destination ID including the K bits. When the CRC operation is successful, the V2X receiving terminal may obtain information of the remaining K-L bits constituting the destination ID through the bit field of the sidelink control information.

Therefore, the V2X receiving terminal can construct a destination ID consisting of K bits by using the L bits of information used for CRC demasking and the remaining K-L bits of information sent through the bit field of the side link control information, and can determine whether the destination ID matches the destination ID received from the higher layer by comparison.

FIG. 12 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

In FIG10, the destination ID of the V2X receiving terminal is masked by CRC and transmitted, and in FIG11, a part of the information on the destination ID of the V2X receiving terminal is masked by CRC and transmitted, and the remaining part of the information on the destination ID is transmitted through the bit field of the sidelink control information. However, in FIG12, the information on the destination ID of the V2X receiving terminal is transmitted through the bit field and CRC of the sidelink control information and through the header of the MAC PDU transmitted via the sidelink data channel.

As shown in Figures 10 and 11, in Figure 12, the time point at which the V2X receiving terminal obtains the destination ID from the higher layer may be any time point before the V2X receiving terminal performs CRC demasking. The V2X receiving terminal that receives the side link control information from the V2X transmitting terminal may decode the side link control information, and may perform CRC demasking by performing an XOR operation on the ID obtained by the V2X receiving terminal from the higher layer and the CRC constituting the side link control information.

The V2X receiving terminal may perform a CRC operation by using the demasked CRC, and when the CRC operation is unsuccessful, the V2X receiving terminal may delete the side link control information from the buffer without storing the side link control information. When the CRC operation is successful, the V2X receiving terminal may obtain the remaining information of the destination ID from the bit field of the side link control information (ie, ID-A in FIG. 12 ), and may check whether the ID in the bit field matches the ID obtained by the V2X receiving terminal from the higher layer.

When the IDs do not match each other, the V2X receiving terminal may delete the side link control information from the buffer without storing the side link control information. When the IDs match each other, the V2X receiving terminal may obtain the location of the time/frequency resource of the side link data information indicated by the side link control information, and may decode the side link data information.

The V2X receiving terminal decoding the sidelink data information may obtain the remaining information (ID-B) of the destination ID through the header of the MAC PDU included in the sidelink data information.

The V2X receiving terminal can construct the destination ID by using some information of the destination ID used for CRC demasking and some information of the destination ID sent through the bit field of the side link control information (ID-A), and some information of the destination ID sent through the header of the MAC PDU of the side link data information (ID-B), and can determine whether the destination ID matches the destination ID obtained by the V2X receiving terminal from the higher layer.

For example, it may be assumed that the destination ID includes K bits and L bits are used for CRC masking. In addition, it is assumed that N bits of destination ID information are transmitted through the bit field of the sidelink control information, and the remaining K-L-N bits of destination ID information are transmitted through the header of the MAC PDU constituting the sidelink data information. In this case, the V2X receiving terminal may perform CRC demasking by using the MSB L bits or LSB L bits of the destination ID including K bits.

When the CRC operation is successful, N bits of information constituting the destination ID can be obtained through the bit field of the side link control information (ID-A).

The V2X receiving terminal can obtain the K-L-N bits of information constituting the destination ID through the header of the MAC PDU that constitutes the side link data information (ID-B).

Therefore, the V2X receiving terminal can construct a K-bit destination ID by using the L bits of information used for CRC demasking and the remaining N bits of ID information (ID-A) sent through the bit field of the side link control information, and the K-L-N bits of the destination ID (ID-B) including the header of the MAC PDU constituting the side link data information, and can determine by comparison whether the destination ID matches the destination ID received by the V2X receiving terminal from the higher layer.

When the destination IDs match each other, the V2X receiving terminal may transmit the decoded side link data information to the higher layer. When the destination IDs do not match each other, the V2X receiving terminal may delete the decoded side link data information from the buffer.

FIG. 13 is a diagram illustrating a method in which a V2X transmitting terminal transmits a destination ID according to another embodiment of the present disclosure.

Unlike FIGS. 9 to 12 , in FIG. 13 , the K bits constituting the destination ID are not CRC-masked and can be used for scrambling the sidelink control channel that transmits the sidelink control information.

The V2X transmitting terminal may obtain the ID (destination ID) information of the V2X receiving terminal including K bits from the higher layer. In this case, in V2X unicast communication, the ID information may be the ID indicating the receiving terminal. In V2X multicast communication, the ID information may be the ID indicating the receiving group.

The V2X transmitting terminal may generate side link control information and may add a cyclic redundancy check (CRC) to the generated side link control information. That is, when it is assumed that the side link control information includes A bits and the CRC includes L bits, the side link control information to which the CRC is added may include A+L bits.

The V2X transmitting terminal may perform channel coding on the side link control information to which CRC is added.

The channel-coded side link control information can be scrambled by using a sequence generated by using at least one of the cell ID, the transmitting terminal ID (source ID) and the receiving terminal ID (destination ID) as an initial value. In this case, scrambling can be performed by performing a modulo 2 operation on the sum of the bits constituting the side link control information and the bits constituting the scrambling sequence. When it is assumed that the bits constituting the side link control information are b(0), b(1), ..., and b(M-1) and the bits constituting the scrambling sequence are c(i) (in this case, i ranges from 0 to the sequence length -1), scrambling can be performed by performing a modulo 2 operation on the result of b(i)+c(i). The scrambled side link control information can be generated as symbols by a modulation process and can be mapped to the resources (resource elements) of the side link control channel.

FIG. 14 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

The V2X receiving terminal may obtain a destination ID that can be used by the V2X receiving terminal from the higher layer. In this case, the destination ID may be one of an ID for unicast communication, an ID for multicast communication, and an ID for broadcast communication. In this case, although the time point at which the destination ID is obtained from the higher layer is the first starting point in FIG. 14, the present disclosure is not limited thereto. That is, in FIG. 14, the time point at which the ID is obtained from the higher layer may be any time point before the V2X receiving terminal performs descrambling of the sidelink control channel.

The V2X receiving terminal that receives the sidelink control channel from the V2X transmitting terminal may descramble the sidelink control channel using the destination ID obtained from the higher layer.

The V2X receiving terminal may perform descrambling, may decode the side link control information, and may then perform a CRC operation. When the descrambled side link control channel passes the CRC operation, it may be determined that the descrambling is successful. The V2X receiving terminal may obtain the side link control information transmitted via the side link control channel.

The V2X receiving terminal can obtain the location of the time/frequency resources of the sidelink data information from the sidelink control information, and can decode the sidelink data information.

When the sidelink control information is decoded and the subsequent CRC operation is unsuccessful, it may be determined that the descrambling has failed. When the descrambling has failed, the V2X receiving terminal may delete the sidelink control information from the buffer without storing the sidelink control information. When the buffer stores the sidelink data information, the V2X receiving terminal may delete both the sidelink control information and the sidelink data information from the buffer.

Some information of the destination ID may be used as an initial value for generating a scrambling sequence for the sidelink control channel, and the remaining information of the destination ID may be transmitted via a bit field of control information transmitted via the sidelink control channel. In this case, the operation of the V2X receiving terminal may be similar to that of FIG. 11 .

In addition, some information of the destination ID may be used as an initial value for generating a scrambling sequence of a sidelink control channel, some information of the destination ID may be transmitted through a bit field of control information transmitted through the sidelink control channel, and the remaining information of the destination ID may be transmitted through a MAC PDU header transmitted through a sidelink data channel. In this case, the operation of the V2X receiving terminal may be similar to that of FIG. 12 .

FIG. 15 is a diagram illustrating a method in which a V2X transmitting terminal transmits a destination ID according to another embodiment of the present disclosure.

In Fig. 9, the destination ID is masked by the CRC of the side link control information and transmitted, and in Fig. 13, the destination ID is used to initialize the scrambling sequence for scrambling the side link control channel. However, in Fig. 15, both methods of Figs. 9 and 13 are used.

The V2X transmitting terminal may obtain the ID (destination ID) information of the V2X receiving terminal including K bits from the higher layer. In this case, in V2X unicast communication, the ID information may be the ID indicating the receiving terminal. In V2X multicast communication, the ID information may be the ID indicating the receiving group.

The V2X transmitting terminal can generate side link control information.

The V2X transmitting terminal may add a cyclic redundancy check (CRC) to the generated side link control information. That is, when it is assumed that the side link control information includes A bits and the CRC includes L bits, the side link control information to which the CRC is added may include A+L bits. In this case, some or all of the K bits of the ID may be masked by a CRC including L bits constituting the side link control information.

In more detail, when the size of the ID is K bits and K>L, the MSB L bits or LSB L bits of the K bits may be used for CRC masking. In this case, the CRC masking may refer to performing a bitwise exclusive OR (XOR) operation on the L bits constituting the CRC and the MSB L bits (or LSB L bits) of the K bits constituting the ID. The remaining (K-L) bits of the K bits constituting the ID that are not used for the CRC mask may be sent in a field of the sidelink control information (SCI), or may be sent through a header of a MAC PDU sent via a sidelink data channel.

There may be other combinations as follows: L bits of the K bits constituting the ID may be used for the CRC mask, N bits of the remaining (K-L) bits may be sent in the field of the sidelink control information (K-L>N), and the remaining (K-L-N) bits may be sent through the header of the MAC PDU.

As another example, when the size of the ID is K bits, the number of bits of the CRC is L, and K=L, all K bits constituting the ID may be used for the CRC mask.

As another example, when K<L, K bits constituting the ID may be used for the CRC mask by performing an XOR operation on the MSB K bits or the LSB K bits among the L bits constituting the CRC.

The V2X transmitting terminal may perform channel coding on the side link control information to which the CRC masked with the destination ID is added.

The channel-coded side link control information may be scrambled by using a sequence generated by using at least one of a cell ID, a transmitting terminal ID (source ID), and a receiving terminal ID (destination ID) as an initial value. In this case, scrambling may be performed by performing a modulo 2 operation on the sum of the bits constituting the side link control information and the bits constituting the scrambling sequence. For example, when it is assumed that the bits constituting the side link control information are b(0), b(1), ..., and b(M-1) and the bits constituting the scrambling sequence are c(i) (in this case, i ranges from 0 to the sequence length -1), scrambling may be performed by performing a modulo 2 operation on the result of b(i)+c(i).

The scrambled sidelink control information may be generated into symbols through a modulation process and may be mapped to resources (resource elements) of a sidelink control channel.

FIG. 16 is a diagram illustrating an operation of a V2X receiving terminal according to another embodiment of the present disclosure.

In detail, FIG. 16 is a diagram illustrating an operation of a V2X receiving terminal when the V2X transmitting terminal operates according to FIG. 15 .

The V2X receiving terminal may obtain a destination ID that can be used by the V2X receiving terminal from a higher layer. In this case, the destination ID may be one of an ID for unicast communication, an ID for multicast communication, and an ID for broadcast communication. Although the time point at which the destination ID is obtained from the higher layer is the first starting point, the present disclosure is not limited thereto. That is, in FIG. 16 , the time point at which the ID is obtained from the higher layer may be any time point before the terminal performs CRC demasking.

The V2X receiving terminal that receives the side link control information from the V2X transmitting terminal may decode the side link control information and may perform CRC demasking by performing an XOR operation on the ID obtained by the V2X receiving terminal from the higher layer and the CRC constituting the side link control information.

The V2X receiving terminal may perform a CRC operation by using the demasked CRC, and when the CRC operation is successful, the V2X receiving terminal may perform descrambling. In this case, as described with reference to FIG. 15 , a sequence for descrambling may be generated by using a destination ID received by the V2X receiving terminal from a higher layer.

When the descrambling is successful, the V2X receiving terminal can obtain the sidelink control information sent via the sidelink control channel. The V2X receiving terminal can obtain the location of the time/frequency resource of the sidelink data information from the sidelink control information, and can decode the sidelink data information.

When the CRC operation is unsuccessful, the V2X receiving terminal may delete the sidelink control information from the buffer without storing the sidelink control information. When the V2X receiving terminal stores the sidelink data information, the V2X receiving terminal may delete both the sidelink control information and the sidelink data information from the buffer.

As described with reference to FIGS. 11 and 12 , some information of the destination ID may be transmitted through the bit field of the control information transmitted via the sidelink control channel. In this case, the operation of the V2X receiving terminal after successful descrambling may be similar to the operation after successful CRC demasking in FIG. 11 . In addition, some information of the destination ID may be transmitted through the bit field of the control information transmitted via the sidelink control channel, and the remaining information of the destination ID may be transmitted through the MAC PDU header transmitted via the sidelink data channel. In this case, the operation of the V2X receiving terminal after successful descrambling may be similar to the operation after successful CRC demasking in FIG. 12 .

FIG. 17 is a diagram illustrating a method of notifying pairing of a V2X transmitting terminal and a V2X receiving terminal according to an embodiment of the present disclosure.

Specifically, FIG17 is a diagram showing that a base station should send a measurement indication (measurement indication of FIG7 ) to a V2X transmitting terminal and a V2X receiving terminal at the same time, or a base station should send a side link transmission and reception indication (side link grant of TX and side link grant of RX of FIG8 ) to a V2X transmitting terminal and a V2X receiving terminal at the same time according to an embodiment.

For example, in V2X unicast communication, a V2X transmitting terminal and a V2X receiving terminal may be paired to perform communication. In this case, many pairs of transmitting terminals and receiving terminals for unicast communication may exist in a cell controlled by one base station. In this case, because the base station sends a measurement indication or a sidelink grant to each terminal through a UE-specific DCI, the overhead of the control information for the sidelink communication may increase. In addition, as described with reference to FIGS. 7 and 8, because the base station may send a measurement indication or a sidelink grant to each of the paired V2X transmitting terminal and the V2X receiving terminal, the overhead may further increase. This overhead problem may occur not only in unicast communication, but also in multicast communication.

Unlike unicast communication, in V2X multicast communication, there may be one transmitting terminal and two or more receiving terminals. In multicast communication, when the base station independently sends a measurement indication or a sidelink authorization to each terminal, unnecessary overhead may increase. For example, the base station may independently send information about the terminal to which the measurement signal is to be sent through the measurement indication and the terminal to which the measurement signal is to be received, as well as parameters related to the sending and receiving of the measurement signal, to each terminal through a UE-specific DCI. Assume that there is one transmitting terminal and 10 receiving terminals in the multicast communication. In this case, because the base station should send the same information (an indicator indicating the reception of the measurement signal and parameters for receiving the measurement signal, such as the time, frequency resource, or sequence index for sending the measurement signal) to each of the 10 receiving terminals, the signaling overhead may increase unnecessarily.

To solve this problem, a method of transmitting the same information to be transmitted to two or more terminals through group common DCI instead of UE-specific DCI is shown in FIG 17. In more detail, K terminal pairs may exist in a cell, and each terminal pair may perform unicast or multicast communication.

For example, when all K terminal pairs perform unicast communication, each terminal pair may include a V2X transmitting terminal and a V2X receiving terminal. In this case, as shown in (a) of FIG. 17 , the base station may send a command for transmitting a measurement signal (or a side link grant for TX) or receiving a measurement signal (or a side link grant for RX) to each terminal pair through 2 bits.

In more detail, it may be assumed that K=4 (which means there are four terminal pairs) and all terminal pairs perform unicast communication. In this case, the base station may transmit a group common DCI including 4 (four terminal pairs)×2 (unicast communication)=8 bits to the four terminal pairs.

Each terminal pair may receive the group-common DCI by detecting a radio network temporary identifier (RNTI) (e.g., a V2X group-common RNTI) that is different from the RNTI used in cellular communication (e.g., a cell (C)-RNTI) or the RNTI (e.g., a V2X C-RNTI) that is specifically sent by the UE to each terminal for sidelink communication.

In this case, the base station can notify each terminal pair through RRC signaling which part of the group common DCI the terminal pair should use. For example, the base station can notify the starting point by notifying the first terminal pair of four terminal pairs that the first terminal pair should use information starting from the first bit, the second terminal pair should use information starting from the third bit, and the third terminal pair should use information starting from the fifth bit.

The information about which bits each terminal pair should use from the starting point is related to the number of terminals constituting each terminal pair. For example, in unicast information, since the number of terminals constituting each terminal pair is 2, 2 bits can be used starting from the starting point (starting bit) notified by the base station through RRC signaling. In addition, each terminal pair needs to know which bit of the 2 bits (a0 and a1 in Figure 17) the terminal pair should use. This can be predetermined. For example, the transmitting terminal can use the front bit, and the receiving terminal can use the back bit. Optionally, the base station can notify each terminal of information about which bit should be used through additional signaling.

As another example, all K terminal pairs perform multicast communication, and each terminal pair may include one V2X transmitting terminal and two or more V2X receiving terminals. For example, each terminal pair may include N terminals. In this case, as shown in (b) of FIG. 17 , the base station may send a command for sending a measurement signal (or transmitting side link control information and data information) or receiving a measurement signal (or receiving side link control information and data information) to each terminal pair through N bits.

In more detail, it can be assumed that K=4, so that there are four terminal pairs, and all terminal pairs perform multicast communication. In this case, the base station can send a group common DCI including 4 (four terminal pairs)×N (multicast communication)=4N bits to the four multicast terminal pairs.

Each terminal pair may receive the group-common DCI for multicast communication by detecting an RNTI (e.g., a V2X multicast group-common RNTI) that is different from the RNTI (e.g., C-RNTI) used in cellular communication, an RNTI (e.g., a V2X multicast group-common RNTI) that the UE specifically sends to each terminal for sidelink communication (e.g., a V2X C-RNTI), or an RNTI sent to a unicast terminal pair via a group-common DCI.

In this case, the base station can notify each terminal pair through RRC signaling which part of the group common DCI the terminal pair should use. For example, the base station can notify the starting point by notifying the first terminal pair of four terminal pairs that the first terminal pair should use information starting from the first bit, the second terminal pair should use information starting from the third bit, and the third terminal pair should use information starting from the fifth bit.

The information about which bits each terminal pair should use starting from the starting point is related to the number of terminals constituting each terminal pair. For example, when the number of terminals constituting each terminal pair in multicast communication is 5, 5 bits can be used starting from the starting point (starting bit) notified by the base station through RRC signaling. The number of terminals constituting each terminal pair in multicast communication can be obtained in advance by each terminal through high-level information in the V2X link configuration step, or can be obtained by the terminal through additional RRC signaling. In the above example, each terminal pair needs to know which bit of the 5 bits the terminal pair should use. This can be predetermined. For example, the V2X transmitting terminal can use the frontmost bit, and the V2X receiving terminal can use the next bit. Optionally, the base station can notify each terminal of information about which bit should be used through additional signaling.

In (a) and (b) of Figure 17, the base station may notify the starting point of the group common DCI that should be used by each terminal pair, and may fix the length of the group common DCI that should be used by each terminal pair according to the number of terminals constituting each terminal pair. The bit information to be used by each terminal in each terminal pair may be predetermined according to the functions of the terminals constituting each terminal pair (ie, the first bit is used by the transmitting terminal and the remaining bits are used by the receiving terminal), or may be notified to the terminal by the base station through additional signaling.

In (a) of Fig. 17, all K terminal pairs perform unicast communication, and in (b) of Fig. 17, all K terminal pairs perform multicast communication. However, even when terminal pairs performing unicast communication and multicast communication coexist, the embodiments of the present disclosure can be applied.

As shown in (c) of Figure 17, it can be assumed that there are four terminal pairs, two terminal pairs perform unicast communication, and the remaining two terminal pairs perform group communication. In addition, it can be assumed that, in the two terminal pairs performing multicast communication, the first terminal pair includes 5 terminals and the second terminal pair includes 10 terminals. In this case, the bits constituting the group common DCI are shown in (c) of Figure 17.

(d) of FIG17 shows bits constituting a group common DCI according to another embodiment.

In (d) of Figure 17, it is assumed that a terminal pair performing unicast communication and a terminal pair performing multicast communication coexist, as in (c) of Figure 17. In this case, the bit information to be used by each terminal pair can be notified to each terminal by the base station through dedicated RRC signaling or public RRC signaling. For example, the first terminal pair can be a0, and the second terminal pair can be a1. In this case, the first terminal pair or the second terminal pair can perform unicast communication or multicast communication.

When the bit information to be used by each terminal pair is set to "1", the V2X transmitting terminal may transmit a measurement signal. Optionally, the V2X transmitting terminal may transmit side link control information or data information. The V2X receiving terminal may receive the measurement signal. Optionally, the V2X receiving terminal may receive side link control information or data information.

When the bit information to be used by each terminal pair is set to "0", the V2X transmitting terminal may not transmit the measurement signal. Optionally, the V2X transmitting terminal may not transmit the side link control information or the data information. The V2X receiving terminal may not receive the measurement signal. Optionally, the V2X receiving terminal may not receive the side link control information or the data information.

FIG. 18 is a diagram illustrating the operation and process of a terminal for side link measurement according to an embodiment of the present disclosure.

A terminal present within the coverage of a base station may receive a synchronization signal sent from the base station, may perform a downlink time-frequency synchronization process, and may receive information for sidelink measurement from the base station. The information for sidelink measurement may include, for example, at least one of a sequence index of a measurement signal, a time resource for sending the measurement signal, a frequency resource, and a transmission period. The information for sidelink measurement may be sent by the base station to the terminal through system information or UE-specific RRC parameters.

The terminal to perform sidelink measurement may determine whether there is sidelink control information or data information to be sent by the terminal via the sidelink. When there is no information, the terminal may not send a sidelink measurement signal, or when there is a measurement signal being sent, the terminal may stop sending the measurement signal. When the information exists, the terminal may determine the connection status with the base station.

When the terminal does not maintain a connection state with the base station (ie, an RRC idle state), the terminal may perform an RRC connection configuration procedure to maintain a connection state with the base station.

When there is side link control information or data information to be sent via the side link, and the terminal maintains a connection state with the base station or performs a connection with the base station through an RRC connection configuration process, the terminal can determine whether a command for sending a measurement signal is received from the base station. The command for sending the measurement signal can be sent by the base station to the terminal through RRC signaling, MAC CE, UE-specific DCI (see Figures 7 and 8), or group common DCI (see Figure 17).

A terminal that receives a command for sending a measurement signal from a base station may send a measurement sequence scrambled by using a destination ID configured from a high layer or a measurement sequence generated by using a destination ID. In this case, the measurement sequence may refer to a reference signal for sidelink channel quality measurement, and may refer to at least one of a DMRS for sidelink control information or data information, a sidelink synchronization signal, a DMRS for a sidelink broadcast channel, and a CSI-RS for a sidelink channel. In addition, the channel quality in the channel quality measurement may refer to at least one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), a channel quality information (CQI), a rank indicator (RI), a precoder matrix indicator (PMI), a CSI-RS resource index (CRI), and a layer indicator (LI).

In the above example, when the sidelink measurement signal is a CSI-RS for measuring the quality of the sidelink channel or a DMRS transmitted via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel transmitted by the V2X transmitting terminal. That is, when there is no sidelink data transmission, the V2X transmitting terminal does not transmit the sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel for sidelink transmission scheduled by the base station through DCI. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of the resource for transmitting the V2X sidelink data channel obtained by the V2X transmitting terminal through a sensing process in a resource pool, and the resource pool is configured by the V2X transmitting terminal through system information or RRC for sidelink transmission from the base station. In the above example, the sensing process may refer to energy measurement of a sidelink control channel or a sidelink data channel, or RSRP measurement from a DMRS transmitted via a sidelink control channel or a sidelink data channel. As another example, the sensing process may refer to a decoding process of control information transmitted via a sidelink control channel. As another example, the sensing process may refer to the above two operations (ie, energy measurement and decoding process of control information).

The V2X receiving terminal may receive and decode the sidelink control information from the V2X transmitting terminal. The V2X receiving terminal may obtain the time and/or frequency resource information of the sidelink data channel from the decoded control information. The V2X receiving terminal may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting terminal may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving terminal. As another example, information about the bandwidth of the transmitted sidelink measurement signal may be sent by the V2X transmitting terminal to the V2X receiving terminal via the sidelink control information. Therefore, in the above example, the V2X receiving terminal may decode the sidelink control information and obtain information about the bandwidth of the sidelink measurement signal.

In FIG. 18 , it has been assumed that both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. In addition, a resource allocation method in which the V2X transmitting terminal operates in an RRC connection state with the base station (the V2X transmitting terminal is scheduled using transmission resources of side link control information and data information from the base station). However, this is merely an example, and the present disclosure is not limited thereto. The V2X transmitting terminal and the V2X receiving terminal may operate in various situations.

For example, the V2X transmitting terminal may exist within the coverage of the base station, and the V2X receiving terminal may exist outside the coverage. As another example, the V2X transmitting terminal may exist within the coverage of base station-1, and the V2X receiving terminal may exist within the coverage of base station-2. In this case, the process of FIG. 18 may be repeatedly used.

Both the V2X transmitting terminal and the V2X receiving terminal may exist outside the coverage of the base station. In this case, the V2X transmitting terminal and the V2X receiving terminal may not perform RRC connection configuration with the base station. Therefore, in this case, in FIG. 18, the operation of determining the RRC connection of the V2X terminal and the operation of determining whether there is an indication from the base station for sending a side link measurement signal may be omitted. That is, the V2X transmitting terminal may determine whether there is side link control information and/or data information to be sent, and may send a side link measurement signal when the information exists. Otherwise, the V2X transmitting terminal may not send a side link measurement signal, or when there is a side link measurement signal being sent, the V2X transmitting terminal may stop sending the side link measurement signal.

In addition, since there is no base station in the above example, the V2X transmitting terminal can directly select resources for the V2X transmitting terminal through a sensing process in a pre-configured resource pool, as shown in FIG7 and FIG8. In this case, in FIG18, the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting the side link measurement signal can be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process can be additionally included. The V2X transmitting terminal can select the resources to be transmitted, and can transmit the side link measurement signal through one of the methods of FIG18.

As another example, the V2X transmitting terminal may exist within the coverage of the base station, but may operate in a state where there is no RRC connection configuration with the base station. In this case, the V2X transmitting terminal may directly select resources for the V2X transmitting terminal through a sensing process in a resource pool configured by the base station, as described with reference to FIGS. 7 and 8 . In this case, in FIG. 18 , the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting a side link measurement signal may be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process may be additionally included. The V2X transmitting terminal may select resources to be transmitted, and may transmit a side link measurement signal through one of the methods of FIG. 18 .

FIG. 19 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

A terminal present within the coverage of a base station may receive a synchronization signal sent from the base station, may perform a downlink time-frequency synchronization process, and may receive information for sidelink measurement from the base station. The information for sidelink measurement may include, for example, at least one of a sequence index of a measurement signal, a time resource for sending the measurement signal, a frequency resource, and a transmission period. The information for sidelink measurement may be sent by the base station to the terminal through system information or UE-specific RRC parameters.

In FIG18 , it may be determined whether to perform side link measurement only for a terminal for which there is side link control information or data information to be transmitted via a side link. However, FIG19 shows the operation of a terminal for performing side link measurement even when there is no side link control information or data information to be transmitted via a side link. That is, a terminal present within the coverage of a base station may determine the connection status with the base station.

When the terminal does not maintain a connection state with the base station (ie, RRC idle state), the terminal may perform an RRC connection configuration process to maintain a connection state with the base station. When the terminal maintains a connection state or the terminal performs a connection with the base station through an RRC connection configuration process, the terminal may determine whether a command for sending a measurement signal is received from the base station. The command for sending the measurement signal may be sent by the base station to the terminal through RRC signaling, MAC CE, UE-specific DCI (see Figures 7 and 8), or group common DCI (see Figure 17).

A terminal that receives a command for sending a measurement signal from a base station may send a measurement sequence scrambled by using a destination ID configured from a high layer or a measurement sequence generated by using a destination ID. In this case, the measurement sequence may refer to a reference signal for sidelink channel quality measurement, and may refer to at least one of a DMRS for sidelink control information or data information, a sidelink synchronization signal, a DMRS for a sidelink broadcast channel, and a CSI-RS for a sidelink channel. In addition, the channel quality in the channel quality measurement may refer to at least one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), a channel quality information (CQI), a rank indicator (RI), a precoder matrix indicator (PMI), a CSI-RS resource index (CRI), and a layer indicator (LI).

In the above example, when the sidelink measurement signal is a CSI-RS for measuring the quality of the sidelink channel or a DMRS transmitted via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel transmitted by the V2X transmitting terminal. That is, when there is no sidelink data transmission, the V2X transmitting terminal does not transmit the sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel for sidelink transmission scheduled by the base station through DCI. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of the resource for transmitting the V2X sidelink data channel obtained by the V2X transmitting terminal through a sensing process in a resource pool, wherein the resource pool is configured by the V2X transmitting terminal through system information or RRC for sidelink transmission from the base station. In the above example, the sensing process may refer to the energy measurement of the sidelink control channel or the sidelink data channel, or the RSRP measurement from the DMRS transmitted via the sidelink control channel or the sidelink data channel. As another example, the sensing process may refer to the decoding process of the control information transmitted via the sidelink control channel. As another example, the sensing process may refer to the above two operations (ie, energy measurement and decoding process of control information).

The V2X receiving terminal may receive and decode the sidelink control information from the V2X transmitting terminal. The V2X receiving terminal may obtain the time and/or frequency resource information of the sidelink data channel from the decoded control information. The V2X receiving terminal may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting terminal may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving terminal. As another example, information about the bandwidth of the transmitted sidelink measurement signal may be sent by the V2X transmitting terminal to the V2X receiving terminal via the sidelink control information. Therefore, in the above example, the V2X receiving terminal may decode the sidelink control information and obtain information about the bandwidth of the sidelink measurement signal.

In FIG. 18 , it has been assumed that both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. In addition, a resource allocation method in which the V2X transmitting terminal operates in an RRC connection state with the base station (the V2X transmitting terminal is scheduled using transmission resources of side link control information and data information from the base station). However, this is merely an example, and the present disclosure is not limited thereto. The V2X transmitting terminal and the V2X receiving terminal may operate in various situations.

For example, the V2X transmitting terminal may exist within the coverage of the base station, and the V2X receiving terminal may exist outside the coverage. As another example, the V2X transmitting terminal may exist within the coverage of base station-1, and the V2X receiving terminal may exist within the coverage of base station-2. In this case, the process of FIG. 18 may be repeatedly used.

Both the V2X transmitting terminal and the V2X receiving terminal may exist outside the coverage of the base station. In this case, the V2X transmitting terminal and the V2X receiving terminal may not perform RRC connection configuration with the base station. Therefore, in this case, in FIG. 18, the operation of determining the RRC connection of the V2X terminal and the operation of determining whether there is an indication from the base station for sending a side link measurement signal may be omitted. That is, the V2X transmitting terminal may determine whether there is side link control information and/or data information to be sent, and may send a side link measurement signal when the information exists. Otherwise, the V2X transmitting terminal may not send a side link measurement signal, or when there is a side link measurement signal being sent, the V2X transmitting terminal may stop sending the side link measurement signal.

In addition, since there is no base station in the above example, the V2X transmitting terminal can directly select resources for the V2X transmitting terminal through a sensing process in a pre-configured resource pool, as shown in FIG7 and FIG8. In this case, in FIG18, the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting the side link measurement signal can be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process can be additionally included. The V2X transmitting terminal can select the resources to be transmitted, and can transmit the side link measurement signal through one of the methods of FIG18.

As another example, the V2X transmitting terminal may exist within the coverage of the base station, but may operate in a state where there is no RRC connection configuration with the base station. In this case, the V2X transmitting terminal may directly select resources for the V2X transmitting terminal through a sensing process in a resource pool configured by the base station, as described with reference to FIGS. 7 and 8 . In this case, in FIG. 18 , the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting a side link measurement signal may be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process may be additionally included. The V2X transmitting terminal may select resources to be transmitted, and may transmit a side link measurement signal through one of the methods of FIG. 18 .

Although the signal for measurement is transmitted by the terminal (i.e., V2X transmitting terminal) that desires to transmit the side link control information and data information in FIG18 , the operation of FIG19 is not limited thereto. That is, when the base station transmits a command for transmitting the measurement signal, not only the terminal (i.e., V2X transmitting terminal) that desires to transmit the side link control information and data information may transmit the signal for measurement, but also the terminal (i.e., V2X receiving terminal) that desires to receive the side link control information and data information may transmit the signal for measurement.

FIG. 20 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

Although FIG20 has the same process as that of FIG18, FIG20 is different from FIG18 in that the entity that transmits the signal for measurement is the terminal that receives the side link control information and data information. That is, although in FIG18 the terminal that transmits the side link where there is the side link control information and data information to be transmitted transmits the measurement signal, in FIG20, the terminal that receives the side link where there is the side link control information and data information to be received transmits the measurement signal.

Therefore, similar to FIG. 20, in FIG. 20, a terminal present in the coverage of a base station may receive a synchronization signal sent from the base station, and may perform a downlink time-frequency synchronization process, and may receive information for side link measurement from the base station. The information for side link measurement may include, for example, at least one of a sequence index of a measurement signal, a time resource for sending a measurement signal, a frequency resource, and a transmission period. The information for side link measurement may be sent by the base station to the terminal through system information or UE-specific RRC parameters.

A terminal that is to perform sidelink measurement may determine whether there is sidelink control information or data information to be sent by the terminal via the sidelink.

When there is no information, the terminal may not send the side link measurement signal, or when there is a measurement signal being sent, the terminal may stop sending the measurement signal. When there is such information, the terminal may determine the connection status with the base station.

When the terminal does not maintain a connection state with the base station (ie, an RRC idle state), the terminal may perform an RRC connection configuration procedure to maintain a connection state with the base station.

When there is side link control information or data information to be sent via the side link, and the terminal maintains a connection state with the base station or performs a connection with the base station through an RRC connection configuration process, the terminal can determine whether a command for sending a measurement signal is received from the base station. The command for sending the measurement signal can be sent by the base station to the terminal through RRC signaling, MAC CE, UE-specific DCI (see Figures 7 and 8), or group common DCI (see Figure 17).

The terminal receiving the command to transmit the measurement signal from the base station may transmit the measurement sequence scrambled by using the destination ID configured from the higher layer or the measurement sequence generated by using the destination ID.

In this case, the measurement sequence may refer to a reference signal for sidelink channel quality measurement, and may refer to at least one of a DMRS for sidelink control information or data information, a sidelink synchronization signal, a DMRS for a sidelink broadcast channel, and a CSI-RS for a sidelink channel. In addition, the channel quality in the channel quality measurement may refer to at least one of a reference signal received power (RSRP), a reference signal received quality (RSRQ), a channel quality information (CQI), a rank indicator (RI), a precoder matrix indicator (PMI), a CSI-RS resource index (CRI), and a layer indicator (LI).

In the above example, when the sidelink measurement signal is a CSI-RS for measuring the quality of the sidelink channel or a DMRS transmitted via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel transmitted by the V2X transmitting terminal. That is, when there is no sidelink data transmission, the V2X transmitting terminal does not transmit the sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel for sidelink transmission scheduled by the V2X transmitting terminal through the DCI of the base station. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of the resource for transmitting the V2X sidelink data channel obtained by the V2X transmitting terminal through a sensing process in a resource pool, wherein the resource pool is configured by the V2X transmitting terminal through system information or RRC for sidelink transmission from the base station. In the above example, the sensing process may refer to the energy measurement of the sidelink control channel or the sidelink data channel, or the RSRP measurement from the DMRS transmitted via the sidelink control channel or the sidelink data channel. As another example, the sensing process may refer to the decoding process of the control information transmitted via the sidelink control channel. As another example, the sensing process may refer to the above two operations (ie, energy measurement and decoding process of control information).

The V2X receiving terminal may receive and decode the sidelink control information from the V2X transmitting terminal. The V2X receiving terminal may obtain the time and/or frequency resource information of the sidelink data channel from the encoded control information. The V2X receiving terminal may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting terminal may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving terminal. As another example, information about the bandwidth of the transmitted sidelink measurement signal may be sent by the V2X transmitting terminal to the V2X receiving terminal via the sidelink control information. Therefore, in the above example, the V2X receiving terminal may decode the sidelink control information and obtain information about the bandwidth of the sidelink measurement signal.

In FIG. 18 , it has been assumed that both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. In addition, a resource allocation method in which the V2X transmitting terminal operates in an RRC connection state with the base station (the V2X transmitting terminal is scheduled using transmission resources of side link control information and data information from the base station). However, this is merely an example, and the present disclosure is not limited thereto. The V2X transmitting terminal and the V2X receiving terminal may operate in various situations.

For example, the V2X transmitting terminal may exist within the coverage of the base station, and the V2X receiving terminal may exist outside the coverage. As another example, the V2X transmitting terminal may exist within the coverage of base station-1, and the V2X receiving terminal may exist within the coverage of base station-2. In this case, the process of FIG. 18 may be repeatedly used.

Both the V2X transmitting terminal and the V2X receiving terminal may exist outside the coverage of the base station. In this case, the V2X transmitting terminal and the V2X receiving terminal may not perform RRC connection configuration with the base station. Therefore, in this case, in FIG. 18, the operation of determining the RRC connection of the V2X terminal and the operation of determining whether there is an indication from the base station for sending a side link measurement signal may be omitted. That is, the V2X transmitting terminal may determine whether there is side link control information and/or data information to be sent, and may send a side link measurement signal when the information exists. Otherwise, the V2X transmitting terminal may not send a side link measurement signal, or when there is a side link measurement signal being sent, the V2X transmitting terminal may stop sending the side link measurement signal.

In addition, since there is no base station in the above example, the V2X transmitting terminal can directly select resources for the V2X transmitting terminal through a sensing process in a pre-configured resource pool, as shown in FIG7 and FIG8. In this case, in FIG18, the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting the side link measurement signal can be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process can be additionally included. The V2X transmitting terminal can select the resources to be transmitted, and can transmit the side link measurement signal through one of the methods of FIG18.

As another example, the V2X transmitting terminal may exist within the coverage of the base station, but may operate in a state where there is no RRC connection configuration with the base station. In this case, the V2X transmitting terminal may directly select resources for the V2X transmitting terminal through a sensing process in a resource pool configured by the base station, as described with reference to FIGS. 7 and 8 . In this case, in FIG. 18 , the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting a side link measurement signal may be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process may be additionally included. The V2X transmitting terminal may select resources to be transmitted, and may transmit a side link measurement signal through one of the methods of FIG. 18 .

FIG. 21 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

A terminal present within the coverage of a base station may receive a synchronization signal sent from the base station, may perform a downlink time-frequency synchronization process, and may receive information for sidelink measurement from the base station. The information for sidelink measurement may include, for example, at least one of a sequence index of a measurement signal, a time resource for sending the measurement signal, a frequency resource, and a transmission period. The information for sidelink measurement may be sent by the base station to the terminal through system information or UE-specific RRC parameters.

21 may also be applied to a terminal without base station coverage. In this case, since the terminal may not receive parameters for measuring signal transmission and reception from the base station through system information or UE-specific RRC signaling, the terminal may use predefined (preconfigured) parameters.

A terminal that is to perform sidelink measurement may determine whether there is sidelink control information or data information to be sent by the terminal via the sidelink.

When there is no information, the terminal may not send the side link measurement signal, or when there is a measurement signal being sent, the terminal may stop sending the measurement signal.

When this information exists, the terminal can determine whether to send a measurement signal by comparing a measurement result previously performed by the terminal with a threshold preconfigured (or predefined) by the base station.

That is, when the measurement result previously performed by the terminal is less than the threshold, the terminal may send a signal for measurement. Otherwise, the terminal may not send a measurement signal.

In this case, the measurement result can be one of the following: RSRP measured from the DMRS of the control channel, RSRP measured from the DMRS of the data channel, RSRP measured from the sidelink synchronization signal used to perform sidelink synchronization, RSRP measured from the DMRS of the sidelink broadcast channel, and the Channel State Information Reference Signal (CSI-RS) used to measure the sidelink channel quality.

The terminal receiving the measurement signal may perform measurement by using measurement information configured by the base station or predefined measurement information. The measurement information configured by the base station may include, for example, at least one of a sequence index of the measurement signal, a time resource for receiving the measurement signal, a frequency resource, and a transmission period.

After performing the measurement, the terminal may report the measurement result to the terminal or base station that sends the measurement signal. The resource for reporting the measurement result may be notified by the terminal or base station that sends the measurement signal, or may be derived by the terminal that receives the measurement signal through an association relationship with the resource that sends the measurement signal, as described with reference to Figures 7 and 8. In this case, the measurement result may not always be reported, but only when the measurement result measured by the terminal that receives the measurement signal is equal to or less than a threshold configured (or predefined) by the base station, the measurement result may be reported to the terminal or base station that sends the measurement signal.

In the above example, when the sidelink measurement signal is a CSI-RS for measuring the quality of the sidelink channel or a DMRS transmitted via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel transmitted by the V2X transmitting terminal. When there is no sidelink data transmission, the V2X transmitting terminal does not transmit the sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel for sidelink transmission scheduled by the base station through DCI. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of the resource for transmitting the V2X sidelink data channel obtained by the V2X transmitting terminal through a sensing process in a resource pool, wherein the resource pool is configured by the V2X transmitting terminal through system information or RRC for sidelink transmission from the base station. In the above example, the sensing process may refer to energy measurement of a sidelink control channel or a sidelink data channel, or RSRP measurement from a DMRS transmitted via a sidelink control channel or a sidelink data channel. As another example, the sensing process may refer to a decoding process of control information transmitted via a sidelink control channel. As another example, the sensing process may refer to the above two operations (ie, energy measurement and decoding process of control information).

The V2X receiving terminal may receive and decode the sidelink control information from the V2X transmitting terminal. The V2X receiving terminal may obtain the time and/or frequency resource information of the sidelink data channel from the decoded control information. The V2X receiving terminal may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting terminal may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving terminal. As another example, information about the bandwidth of the transmitted sidelink measurement signal may be sent to the V2X receiving terminal through the sidelink control information. Therefore, in the above example, the V2X receiving terminal may decode the sidelink control information and obtain information about the bandwidth of the sidelink measurement signal.

In FIG. 18 , it has been assumed that both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. In addition, a resource allocation method in which the V2X transmitting terminal operates in an RRC connection state with the base station (the V2X transmitting terminal is scheduled using the transmission resources of the side link control information and data information from the base station). However, this is merely an example, and the present disclosure is not limited thereto. The V2X transmitting terminal and the V2X receiving terminal may operate in various situations.

For example, the V2X transmitting terminal may exist within the coverage of the base station, and the V2X receiving terminal may exist outside the coverage. As another example, the V2X transmitting terminal may exist within the coverage of base station-1, and the V2X receiving terminal may exist within the coverage of base station-2. In this case, the process of FIG. 18 may be repeatedly used.

Both the V2X transmitting terminal and the V2X receiving terminal may exist outside the coverage of the base station. In this case, the V2X transmitting terminal and the V2X receiving terminal may not perform RRC connection configuration with the base station. Therefore, in this case, in FIG. 18, the operation of determining the RRC connection of the V2X terminal and the operation of determining whether there is an indication from the base station for sending a side link measurement signal may be omitted. That is, the V2X transmitting terminal may determine whether there is side link control information and/or data information to be sent, and may send a side link measurement signal when the information exists. Otherwise, the V2X transmitting terminal may not send a side link measurement signal, or when there is a side link measurement signal being sent, the V2X transmitting terminal may stop sending the side link measurement signal.

In addition, since there is no base station in the above example, the V2X transmitting terminal can directly select resources for the V2X transmitting terminal through a sensing process in a pre-configured resource pool, as shown in FIG7 and FIG8. In this case, in FIG18, the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting the side link measurement signal can be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process can be additionally included. The V2X transmitting terminal can select the resources to be transmitted, and can transmit the side link measurement signal through one of the methods of FIG18.

As another example, the V2X transmitting terminal may exist within the coverage of the base station, but may operate in a state where there is no RRC connection configuration with the base station. In this case, the V2X transmitting terminal may directly select resources for the V2X transmitting terminal through a sensing process in a resource pool configured by the base station, as described with reference to FIGS. 7 and 8 . In this case, in FIG. 18 , the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting a side link measurement signal may be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process may be additionally included. The V2X transmitting terminal may select resources to be transmitted, and may transmit a side link measurement signal through one of the methods of FIG. 18 .

FIG. 22 is a diagram illustrating the operation and process of a terminal for side link measurement according to another embodiment of the present disclosure.

Although the terminal to transmit the sidelink control information and the data information determines whether to transmit the measurement signal in FIG. 21 , the terminal to receive the sidelink control information and the data information determines whether to transmit the measurement signal in FIG. 22 .

In more detail, a terminal present in the coverage area of a base station may receive a synchronization signal sent from the base station, may perform a downlink time-frequency synchronization process, and may receive information for sidelink measurement from the base station. The information for sidelink measurement may include, for example, at least one of a sequence index of a measurement signal, a time resource for sending a measurement signal, a frequency resource, and a transmission period. The information for sidelink measurement may be sent by the base station to the terminal through system information or UE-specific RRC parameters.

Similar to Figure 21, the embodiment of Figure 22 can also be applied to a terminal without base station coverage. In this case, because the terminal may not be able to receive parameters for measuring signal transmission and reception from the base station through system information or UE-specific RRC signaling, the terminal can use predefined (preconfigured) parameters.

A terminal that is to perform sidelink measurement may determine whether there is sidelink control information or data information to be sent by the terminal via the sidelink.

When there is no information, the terminal may not send the side link measurement signal, or when there is a measurement signal being sent, the terminal may stop sending the measurement signal.

When this information exists, the terminal may determine whether to send a measurement signal by comparing a measurement result previously performed by the terminal with a threshold value preconfigured (or predefined) by the base station. That is, when the measurement result previously performed by the terminal is less than the threshold value, the terminal may send a signal for measurement. Otherwise, the terminal may not send a measurement signal.

The terminal receiving the measurement signal may perform the measurement by using the measurement information configured by the base station or the predefined measurement information. The measurement information configured by the base station may include, for example, at least one of the sequence index of the measurement signal, the time resource for receiving the measurement signal, the frequency resource, and the transmission period. After performing the measurement, the terminal may report the measurement result to the terminal or the base station that sent the measurement signal.

The resource for reporting the measurement result may be notified by the terminal or base station that transmits the measurement signal, or may be derived by the terminal that receives the measurement signal through an association relationship with the resource that transmits the measurement signal, as described with reference to Figures 7 and 8. In this case, the measurement result may not always be reported, but only when the measurement result measured by the terminal that receives the measurement signal is equal to or less than a threshold configured (or predefined) by the base station, the measurement result may be reported to the terminal or base station that transmits the measurement signal.

In Figure 21, the terminal to send the side link control information and data information compares the measurement result previously performed by the terminal with the threshold. In Figure 22, the terminal to receive the side link control information and data information compares the measurement result previously performed by the terminal with the threshold. However, the comparison process can be performed by a command of the base station regardless of the transmission/reception of the side link control information and data information. That is, the base station can instruct the terminal to perform an operation of comparing the measurement result with the threshold through UE-specific RRC signaling, MAC CE or DCI.

In addition, the process of comparing the measurement result previously performed by the terminal with the threshold is shown in Figures 21 and 22, but the present disclosure is not limited thereto. That is, the terminal may compare the MCS of the previously sent side link control information and data information with the threshold. In this case, it is obvious that the threshold is related to the MCS.

In the above example, when the sidelink measurement signal is a CSI-RS for measuring the quality of the sidelink channel or a DMRS transmitted via a sidelink data channel, the sidelink measurement signal is always within the bandwidth of the sidelink data channel transmitted by the V2X transmitting terminal. When there is no sidelink data transmission, the V2X transmitting terminal does not transmit the sidelink measurement signal. In this case, the bandwidth of the sidelink data channel may refer to the frequency width of the sidelink data channel for sidelink transmission scheduled by the base station through DCI. As another example, the bandwidth of the sidelink data channel may refer to the frequency width of the resource for transmitting the V2X sidelink data channel obtained by the V2X transmitting terminal through a sensing process in a resource pool, wherein the resource pool is configured by the V2X transmitting terminal through system information or RRC for sidelink transmission from the base station. In the above example, the sensing process may refer to energy measurement of a sidelink control channel or a sidelink data channel, or RSRP measurement from a DMRS transmitted via a sidelink control channel or a sidelink data channel. As another example, the sensing process may refer to a decoding process of control information transmitted via a sidelink control channel. As another example, the sensing process may refer to the above two operations (ie, energy measurement and decoding process of control information).

The V2X receiving terminal may receive and decode the sidelink control information from the V2X transmitting terminal. The V2X receiving terminal may obtain the time and/or frequency resource information of the sidelink data channel from the decoded control information. The V2X receiving terminal may indirectly derive information about the bandwidth of the transmitted sidelink measurement signal through the obtained information. In this case, the V2X transmitting terminal may not send additional information about the bandwidth of the sidelink measurement signal to the V2X receiving terminal. As another example, information about the bandwidth of the transmitted sidelink measurement signal may be sent by the V2X transmitting terminal to the V2X receiving terminal through the sidelink control information. Therefore, in the above example, the V2X receiving terminal may decode the sidelink control information and obtain information about the bandwidth of the sidelink measurement signal.

In FIG. 18 , it has been assumed that both the V2X transmitting terminal and the V2X receiving terminal exist within the coverage of the base station. In addition, a resource allocation method in which the V2X transmitting terminal operates in an RRC connection state with the base station (the V2X transmitting terminal is scheduled using the transmission resources of the side link control information and data information from the base station). However, this is merely an example, and the present disclosure is not limited thereto. The V2X transmitting terminal and the V2X receiving terminal may operate in various situations.

For example, the V2X transmitting terminal may exist within the coverage of the base station, and the V2X receiving terminal may exist outside the coverage. As another example, the V2X transmitting terminal may exist within the coverage of base station-1, and the V2X receiving terminal may exist within the coverage of base station-2. In this case, the process of FIG. 18 may be repeatedly used.

Both the V2X transmitting terminal and the V2X receiving terminal may exist outside the coverage of the base station. In this case, the V2X transmitting terminal and the V2X receiving terminal may not perform RRC connection configuration with the base station. Therefore, in this case, in FIG. 18, the operation of determining the RRC connection of the V2X terminal and the operation of determining whether there is an indication from the base station for sending a side link measurement signal may be omitted. That is, the V2X transmitting terminal may determine whether there is side link control information and/or data information to be sent, and may send a side link measurement signal when the information exists. Otherwise, the V2X transmitting terminal may not send a side link measurement signal, or when there is a side link measurement signal being sent, the V2X transmitting terminal may stop sending the side link measurement signal.

In addition, since there is no base station in the above example, the V2X transmitting terminal can directly select resources for the V2X transmitting terminal through a sensing process in a pre-configured resource pool, as shown in FIG7 and FIG8. In this case, in FIG18, the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from the base station for transmitting the side link measurement signal can be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process can be additionally included. The V2X transmitting terminal can select the resources to be transmitted, and can transmit the side link measurement signal through one of the methods of FIG18.

As another example, the V2X transmitting terminal may exist within the coverage of the base station, but the V2X transmitting terminal may operate in a state where there is no RRC connection configuration with the base station. In this case, the V2X transmitting terminal may directly select resources for the V2X transmitting terminal through a sensing process in a resource pool configured by the base station, as described with reference to FIGS. 7 and 8 . In this case, in FIG. 18 , the operation of the V2X transmitting terminal determining the RRC connection and the operation of the V2X transmitting terminal determining whether there is an indication from several sheets for transmitting the side link measurement signal may be omitted. In addition, the operation of the V2X transmitting terminal selecting resources for the side link control information and data information to be transmitted by the V2X transmitting terminal through a sensing process may be additionally included. The V2X transmitting terminal may select resources to be transmitted, and may transmit the side link measurement signal through one of the methods of FIG. 18 .

FIG. 23 is a diagram illustrating a structure of a terminal according to an embodiment of the present disclosure.

The terminal according to the embodiment of the present disclosure described with reference to FIG23 may be a transmitting terminal or a receiving terminal. In addition, the transmitting terminal may be referred to as a V2X transmitting terminal, and the receiving terminal may be referred to as a V2X receiving terminal.

23, the terminal may include a processor 2301, a transceiver 2302, and a memory 2303. A processor in the present disclosure may be defined as a circuit, an application specific integrated circuit, or at least one processor.

The processor 2301 according to an embodiment of the present disclosure can control the entire operation of the terminal. For example, the processor 2301 can control the signal flow between the frames to perform the operation according to the above-mentioned flowchart. In addition, the processor 2301 can write data to the memory 2303 and read data from the memory 2303. The processor 2301 can perform the functions of the protocol stack required by the communication standard. To this end, the processor 2301 may include at least one processor or microprocessor. Optionally, the processor 2301 may be a part of the processor. In addition, the transceiver 2302 and a part of the processor 2301 may be referred to as a communication processor (CP).

According to an embodiment of the present disclosure, the processor 2301 may control the operation of the terminal described with reference to FIGS. 1 to 23 .

By measuring the link quality between terminals according to an embodiment of the present disclosure, the processor 2301 according to an embodiment of the present disclosure can improve the reliability of data transmission/reception and increase the data rate by adaptively adjusting the link parameters between terminals according to the channel environment in the vehicle communication system. Therefore, the processor 2301 can support more efficient communication between terminals.

According to the transceiver 2302 of the embodiment of the present disclosure, a function for transmitting/receiving a signal via a wireless channel may be performed. For example, the transceiver 2302 may perform a conversion function between a bit string and a baseband signal according to the physical layer standard of the system. For example, during data transmission, the transceiver 2302 may generate a complex symbol by encoding and modulating the transmission bit string. In addition, during data reception, the transceiver 2302 may reconstruct the received bit string by demodulating and decoding the baseband signal. In addition, the transceiver 2302 may up-convert the baseband signal to a radio frequency (RF) band signal, which may then be transmitted through an antenna, and may down-convert the RF band signal received through the antenna to a baseband signal. For example, the transceiver 2302 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), and an analog-to-digital converter (ADC). In addition, the transceiver 2302 may include multiple transmission/reception paths. In addition, the transceiver 2302 may include at least one antenna array, which may include multiple antenna elements. When implemented using hardware, the transceiver 2302 may include a digital circuit and an analog circuit (eg, a radio frequency integrated circuit (RFIC)). The digital circuit and the analog circuit may be implemented as one package. In addition, the transceiver 2302 may include multiple RF chains.

The memory 2303 according to an embodiment of the present disclosure may store data such as basic programs, applications, and configuration information for the operation of the terminal. The memory 2303 may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The memory 2303 may provide stored data according to a request of the processor 2301. The memory 2303 may store at least one of information sent/received by the transceiver 2302 and information generated by the processor 2301.

FIG. 24 is a diagram showing a structure of a base station according to an embodiment of the present disclosure.

24, a base station may include a processor 2401, a transceiver 2402, and a memory 2403. A processor in the present disclosure may be defined as a circuit, an application specific integrated circuit, or at least one processor.

The processor 2401 according to an embodiment of the present disclosure may control the overall operation of the base station. For example, the processor 2401 may control the signal flow between the frames to perform the operation according to the above-mentioned flowchart. In addition, the processor 2401 may write data to the memory 2403 and read data from the memory 2403. The processor 2401 may perform the functions of the protocol stack required by the communication standard. To this end, the processor 2401 may include at least one processor or microprocessor. Optionally, the processor 2401 may be a part of a processor. In addition, the transceiver 2402 and a part of the processor 2401 may be referred to as a communication processor (CP).

According to an embodiment of the present disclosure, the processor 2401 may control the operation of the base station described with reference to FIGS. 1 to 23 .

By measuring the link quality between terminals according to an embodiment of the present disclosure, the processor 2401 according to an embodiment of the present disclosure can improve the reliability of data transmission/reception and increase the data rate by adaptively adjusting the link parameters between terminals according to the channel environment in the vehicle communication system. Therefore, the processor 2401 can support more efficient communication between terminals.

According to the transceiver 2402 of the embodiment of the present disclosure, a function for transmitting/receiving a signal via a wireless channel may be performed. For example, the transceiver 2402 may perform a conversion function between a bit string and a baseband signal according to the physical layer standard of the system. For example, during data transmission, the transceiver 2402 may generate a complex symbol by encoding and modulating the transmission bit string. In addition, during data reception, the transceiver 2402 may reconstruct the received bit string by demodulating and decoding the baseband signal. In addition, the transceiver 2402 may up-convert the baseband signal to an RF band signal, and then transmit the signal through the antenna, and may down-convert the RF band signal received by the antenna to a baseband signal. For example, the transceiver 2402 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, and an ADC. In addition, the transceiver 2402 may include multiple transmission/reception paths. In addition, the transceiver 2402 may include at least one antenna array including multiple antenna elements. When implemented using hardware, the transceiver 2402 may include digital circuits and analog circuits (e.g., radio frequency integrated circuits (RFICs)). Digital circuits and analog circuits may be implemented as one package. In addition, transceiver 2402 may include multiple RF chains.

The memory 2403 according to an embodiment of the present disclosure may store data such as basic programs, application programs, and configuration information for the operation of the base station. The memory 2403 may include a volatile memory, a non-volatile memory, or a combination of a volatile memory and a non-volatile memory. The memory 2403 may provide stored data according to a request of the processor 2401. The memory 2403 may store at least one of information sent/received by the transceiver 2402 and information generated by the processor 2401.

The methods according to the claims or embodiments of the present disclosure described herein may be implemented in the form of hardware, software, or a combination of hardware and software.

When the method is implemented by software, a computer-readable storage medium or a computer program product for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium or the computer program product are configured to be executable by one or more processors in an electronic device. One or more programs include instructions for allowing an electronic device to perform a method according to the claims or embodiments of the present disclosure described herein.

These programs (software modules or software) may be stored in a random access memory (RAM), a nonvolatile memory including a flash memory, a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic disk storage device, a compact disk (CD)-ROM, a digital versatile disk (DVD), another optical storage device, or a cassette tape. Alternatively, the program may be stored in a memory configured by combining some or all of them. In addition, each constituent memory may include a plurality of memories.

In addition, the program may be stored in an attachable storage device accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide LAN (WLAN), or a storage area network (SAN), or a combination thereof. Such a storage device may be connected to the apparatus according to an embodiment of the present disclosure via an external port. In addition, a separate storage device on a communication network may be connected to the apparatus according to an embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, the components included in the present disclosure are represented as singular or plural according to the specific embodiments of the present disclosure described. However, for ease of description, singular or plural representation is appropriately selected, the present disclosure is not limited to singular or plural constituent elements, and even an element represented as a singular element may also be composed of plural elements, and vice versa.

However, the present disclosure may be implemented in different forms and should not be construed as being limited to the embodiments of the present disclosure set forth herein; on the contrary, these embodiments of the present disclosure are provided to make the present disclosure thorough and complete. That is, it is obvious to those of ordinary skill in the art that various modifications may be made based on the technical scope of the present disclosure. In addition, the embodiments of the present disclosure may be implemented in combination. For example, one embodiment of the present disclosure and parts of another embodiment may be combined with each other. In addition, the embodiments of the present disclosure may also be applied to LTE systems, 5G or NR systems, etc., and other modifications may be made based on the technical scope of the embodiments of the present disclosure.

Claims (15)

1. A method performed by a first terminal in a wireless communication system, the method comprising:

Receiving a radio resource control, RRC, message from a base station, wherein the RRC message includes first information about side link channel state information reference signal, CSI-RS, resources and second information about side link CSI reports;

transmitting side link control information SCI to the second terminal based on the first information;

transmitting a side link CSI-RS to the second terminal based on the first information, the second information and the SCI; and

Receiving a side link CSI report from the second terminal based on the side link CSI-RS, as a response to the SCI,

Wherein the side link CSI-RS is transmitted in a resource block for a side link data channel.

2. The method according to claim 1,

Wherein the side link CSI report is used to measure side link channel quality, and the side link channel quality comprises a channel quality indicator CQI and a rank indicator RI.

3. The method according to claim 1,

Wherein the resource blocks for the sidelink data channels are associated with sidelink control channels.

4. A method according to claim 3,

Wherein the side link data channel is associated with V2X unicast communications.

5. A method performed by a second terminal in a wireless communication system, the method comprising:

Receiving side link control information SCI from a first terminal based on first information on side link channel state information reference signal CSI-RS resources;

Receiving a side link CSI-RS from a first terminal based on the first information, second information on the side link CSI report, and the SCI; and

Based on the side link CSI-RS, a side link CSI report is sent to the first terminal, as a response to the SCI,

Wherein the first information and the second information are included in a radio resource control, RRC, message,

Wherein the side link CSI-RS is transmitted in a resource block for a side link data channel.

6. The method according to claim 5,

Wherein the side link CSI report is used to measure side link channel quality, and the side link channel quality comprises a channel quality indicator CQI and a rank indicator RI.

7. The method according to claim 5,

Wherein the resource blocks for the sidelink data channels are associated with sidelink control channels.

8. The method according to claim 7,

Wherein the side link data channel is associated with V2X unicast communications.

9. A first terminal in a wireless communication system, the first terminal comprising:

a transceiver; and

At least one processor coupled to the transceiver and configured to control to:

receiving a radio resource control, RRC, message from the base station, wherein the RRC message includes first information about side link channel state information reference signal, CSI-RS, resources and second information about side link CSI reports,

The side link control information SCI is transmitted to the second terminal based on the first information,

Transmitting a side link CSI-RS to the second terminal based on the first information, the second information, and the SCI, and

Receiving a side link CSI report from the second terminal based on the side link CSI-RS, as a response to the SCI,

Wherein the side link CSI-RS is transmitted in a resource block for a side link data channel.

10. The first terminal of claim 9,

Wherein the side link CSI report is used to measure side link channel quality, and the side link channel quality comprises a channel quality indicator CQI and a rank indicator RI.

11. The first terminal of claim 9,

Wherein the resource blocks for the sidelink data channels are associated with sidelink control channels.

12. The first terminal of claim 11,

Wherein the side link data channel is associated with V2X unicast communications.

13. A second terminal in a wireless communication system, the second terminal comprising:

a transceiver; and

At least one processor coupled to the transceiver and configured to control to:

Based on the first information on the side link channel state information reference signal CSI-RS resource, side link control information SCI is received from the first terminal,

Receiving a side link CSI-RS from a first terminal based on the first information, second information about the side link CSI report, and SCI, and

Based on the side link CSI-RS, a side link CSI report is sent to the first terminal, as a response to the SCI,

Wherein the first information and the second information are included in a radio resource control, RRC, message,

Wherein the side link CSI-RS is transmitted in a resource block for a side link data channel.

14. The second terminal of claim 13,

Wherein the side link CSI report is used to measure side link channel quality, and the side link channel quality comprises a channel quality indicator CQI and a rank indicator RI.

15. The second terminal of claim 13,

Wherein the resource blocks for the sidelink data channels are associated with sidelink control channels.